Letshuoer S12 Ultra Review 

Intro 

Hello, this review and feature covers the latest from the audio brand Letshuoer which goes by the name of Letshuoer S12 Ultra ($169). I’m fairly certain that by now the name “Letshuoer”, as well as the “S12 series” of iems rings many bells within the hearts and minds of the audio faithful. However, for those who haven’t heard of this brand, or this series of iems let me give you a small glimpse into the magnitude of what this series has been to the community at large…

S12 Series 

A few years ago, well, more than a few, the personal audio hobby was absolutely taken over by a certain driver configuration called the planar magnetic driver. Planar drivers offer performance that other drivers simply cannot replicate in the same effortless way. They are very fast with the capacity for tight & rapid transients, and they can come across very dynamic and very clean. There was an explosion around that time (2021) from an iem named the 7Hz Timeless. Sure, there were others which made a mark prior to the Timeless, like the Tin Hifi P1 etc. However, it was the Timeless which truly lit the flame. Anyways, the Timeless started a trend which ultimately would take over the industry. Every brand began coming out with their versions of planar iems, including one of my personal favorite brands…Letshuoer. Letshuoer crafted one of the hottest sets that has hit the market in years named the Letshuoer S12. Thus, the S12 series was born. Folks, this set was absolutely lauded, adored, and spoken of in more chats, threads, posts, and dominated more comment sections across social media than most sets. Well, the Hidizs MP145, 7Hz Timeless, Blon BL-03, and a few others may have something to say about that, but I digress. The Letshuoer S12 dominated folks. Thus, every version and variant of the S12 series also dominated. There have been a handful if you count the Letshuoer X Z Reviews Z12. 

Legacy series

So, we learned about the S12 from Letshuoer, but this series has only gotten better friends. Literally, with every iteration of this series we saw the tech getting better and the end result sounding better. After the S12 came one of my favorite planars from 2022 named the Letshuoer S12 Pro (S12 Pro Review). What a fantastic iem, both in design as well as sound. It was a little bit less peaky, more balanced, and closer to an organic sound. Also, that blue with silver trim design is simply awesome. After the S12 Pro came one of the best planar iems period. I mean, no matter the price too. That being the one, and the only…Letshuoer S12 2024 Edition (S12 2024 Edition Review). Folks, I am still in love with the S12 2024. Ya know, prior to the S12 2024 Letshuoer had actually begun coming up with alternate tunings from alternative series like the Letshuoer S08 (S08 Review) and the pricier Letshuoer S15 (S15 Review). I bring this up because those two sets were some of the first planars that I had ever heard which actually sounded more organic, more earthy. They still had the planar skillset; speed, transient attack-decay, and technical ability, but they sounded more natural. Gone was the “planar timbre” and the 2D soundstage. Fast forward to the S12 2024 Edition and it quite literally trumped all other planars now that Letshuoer has learned as much as they had. Truly, one of the best iems under $200, planar or no planar. Which brings us to the brand new S12 Ultra that I have before me. I am very curious to do a side-by-side between the S12 2024 and the Ultra. At any rate, the S12 series has certainly earned its flowers. Letshuoer deserves every bit of praise. 

Letshuoer 

Now that I’ve gone through a 3,000-foot view “rundown” of the S12 series, I want to brag on Letshuoer in general. Friends, there are a few brands that I seem to just gel with. If you’ve read any of my reviews, then you know there’s about a handful of them that I always have to say something nice about. I have reviewed more than a few Letshuoer iems and I can tell you right now that I have yet to turn one away. This is a brand which makes wise decisions, they feel out the market, they know the market temp, the trends, and they always release products at the right time. You won’t catch Letshuoer releasing 20 sets a year. They make relevant releases, and they do so with “something new” to bring to the table every time. I have only been impressed by this brand for years now folks. If you’d like, check out some of my Letshuoer reviews over the years:

Letshuoer S12 Pro   Letshuoer DZ4    Letshuoer S15    Letshuoer Cadenza 4, Letshuoer S08    Letshuoer S12 2024 Edition    Letshuoer Mystic 8    Letshuoer DX1. 

Well friends, I have had the S12 Ultra in my possession for roughly about three weeks. I wanted to wait for the hype to die down to publish and this is a set that I am not willing to rush out an opinion on. The more I review, the more I realize that to give a proper assessment that I can be sure of… I need to spend at least three weeks getting to know each product. At the least. Needless to say, I have a good idea about the Ultra and I’m happy to talk about it. So, without further ado… the Letshuoer S12 Ultra…

Non-Affiliated Purchasing Links:

–Letshuoer 

–Linsoul 

–Amazon

S12 Ultra Pros

-Build Quality (light, durable, all-alloy) 

-Same design as previous S12 series sets… basically, very nice

-Unboxing experience is solid for the cost

-Smooth, organic sound, very earthy timbre

-Bass isn’t overwhelming, yet is fun

-Warm bass with good note definition, deep and textured

-Midrange has great timbre, no planar metallic edge, nice presence

-Treble is non-fatiguing, smooth, just enough emphasis (a con for some) 

-Detail retrieval is great per the tuning

-Imaging 

S12 Ultra Cons

-Fit can be an issue (find tips which works with your ears) 

-The warm/smooth/non-offensive signature is not as exciting as previous S12 series sets. 

-Treble isn’t as crisp or as brilliant as some may enjoy

-May be too lifted in the sub-bass for some folks

Gear used for testing 

–Shanling UP6

–Shanling UA6 

–Ifi Go Blu 

–Hidizs S9 Pro Plus  

–Shanling H0

–Hidizs AP80 Pro Max 

–Fiio JM21 

–Hiby R3 Pro II

–Hiby R6 Pro II 2025 

–Shanling M1 Plus

–IBasso DX240 with Amp8 MK2 

–Shanling M6 Ultra 

–Fiio Q15

Packaging / Accessories 

Unboxing 

The Letshuoer S12 Ultra arrived at my home in a regular sized rectangular box with a black sleeve covering featuring the name as well as a cool graphic. It’s a nice-looking box. The rest of the unboxing section will be a quick rundown. Anyways, take off the sleeve and you’ll see a black box, open the box and you’ll uncover the gorgeous S12 Ultra chillin’ in foam cut-outs in one panel and right next to them you’ll see the carrying case which is also in foam cut-outs. Inside of the carrying case you see the cable, eartips, and USB type-c dongle dac along with two cable adapters (3.5 / 4.4 threaded jacks). Like I said, I won’t go too far in depth here as I know people like to discover the unboxing themselves. While the S12 Ultra has a nice unboxing for the cost, it certainly isn’t as close to a good experience as the S12 2024 Edition. Still, not bad at all. 

Eartips

Letshuoer added in six eartips in total with two different styles of eartips. The first set I’ll talk about are three pairs (S, M, L) of dark gray silicone tips which come with a wide bore, semi-firm flange, and a relatively rigid stem. I honestly don’t get a good seal with these tips, but I do like a larger bore. The next style of eartips are three pairs (S, M, L) of the same white flange and black stem eartips as Letshuoer has provided in the past. They are a white silicone eartip with a semi-wide bore size and a firm flange. I actually have always liked these tips, and they fit my ears very well. However, I did not end up going with either style provided. I actually went through many eartips in pursuit of the best pairing “sonically” with the S12 Ultra. The eartips that I finally landed in are the Dunu S&S tips. First off, the S&S tips give me a perfect seal, deeper fit, and they have a wider bore than most sets. The wider bore does help pronounce the upper ranges a hair more as well as add just a touch of openness, crispness, and edge detail to the sound. Of course, you’ll need to explore for yourself, but Letshuoer always adds in relevant eartips within their packages. Not bad at all. 

Carrying Case 

Once again Letshuoer provides the same carrying case as we’ve seen with most of their iems. It is a plastic threaded case with a screw-on top, hockey puck style round. I’d say it is just large enough to fit your earphones, the cable and probably the small type-c dongle dac from the packaging. It’s not the largest case I’ve ever seen, but it works. Great for throwing into a bag and not having to worry about your precious earphones getting banged up. If you’ve gotten any recent Letshuoer iems than you know this case. At times the threads are tough to get started when putting in the lid, but it does seal tight, which is nice. 

Type-C Dongle Dac

Letshuoer also added in a type-c & 3.5 single ended dongle dac adapter within the packaging as well. This dongle dac is actually the Letshuoer DT01, valued at $16 US. It’s a very nice touch and a solid extra addition to the package. However, I rarely used this dongle dac just because I do feel the S12 Ultra does much better with more raw power. That said, it certainly doesn’t sound bad by any stretch of the imagination. For my listening I did have to crank the volume pretty high to achieve good loudness. Again, a nice added piece to the overall package, and a nice portable accessory that sounds good in a pinch, out in the market too, and good for anyone who doesn’t want to take their better sources out and about with them. 

Cable 

This brings us to the best accessory provided in the S12 Ultra packaging. That being the cable. So, the included cable is a brown & gray braided cable and comes with two different adapters. Those being a 3.5 single ended, and a 4.4 balanced adapter. To be exact, the cable provided is a 2-pin beautiful, braided cable made up of 392-cores. The cable is actually a silver-plated copper cable and pairs very well sonically with the S12 Ultra. Beyond the sonic benefits, it also pairs well aesthetically with the S12 Ultra. I was very happy that I didn’t have to find another cable or purchase another cable. It’s actually quite nice. Now, the included cable has some nice thickness to it as it isn’t some cheap throw-in wire. Also, it actually seems that Letshuoer was trying to get the aesthetic appearance matched with the S12 Ultra, which is fantastic to see. Just one less thing that I’d have to do. In truth, very few brands actually take the time to find a good cable with a nice aesthetic appeal. So, I definitely applaud Letshuoer for their choice here. It’s a solid cable for sure. 

Build / Design / Internals / Fit 

Build Quality 

The Letshuoer S12 Ultra is just like every other variant in this series as it’s made entirely out of aluminum alloy which is a huge benefit for a few reasons. Namely, they are lightweight and never feel fatiguing to my ears. The S12 Ultra has a very sturdy and durable build as one would expect made out of aluminum. In truth, this entire series has always had good build quality. In fact, build is about the last thing you have to worry about. Anyways, the nozzles are about medium length, not too long or too short. The nozzles are right around 6mm in width which is about standard. Really there isn’t a whole lot to say. Letshuoer always has nice builds, and the S12 Ultra is no exception. 

Design / Aesthetic 

As you may have guessed, or already seen in pictures, the Letshuoer S12 Ultra looks very similar in design to past S12 series sets. In fact, the housing is pretty much identical to those older sets. Same rounded corners, same shape. Habjng said that, the S12 Ultra is still very dope looking. All of this series sets are cool in design. They are smaller housings which fit very well in the ear and the shape is nice. So, the S12 Ultra comes in two color variants, those being “Gun Metal Gray” and “Mocha”. I personally feel that the Mocha colorway is the best looking of the two, but they are both nice. Also, I love the matte texture of the coating as well as you never have to worry about fingerprints and it’s simply a nice look. This is a dope looking set folks. 

Internals 

The Letshuoer S12 Ultra comes with one planar magnetic driver. That is a 14.8 mm driver with some small upgrades. There really isn’t a whole lot to update you on here as far as the driver itself. The changes internally actually come in the design of the acoustic chamber and how they went about the damping of this driver as Letshuoer added in some airflow optimization and they used a different filter density. This change did add a smoother overall sound from previous versions. Anyways, it’s basically the same driver that has made this series what it is with just some different tuning methods. 

Fit / Comfort 

This series has always fit my ears well. I’ve never had an issue whatsoever and every one of these iems has nestled into my ears very well. Now, just like some of the older variants I did have to tip roll to get an optimal seal in my ears, but as far as actual comfort; I love this design and how it fits my ear anatomy. Now, how well the S12 Ultra fits your ears is something that I cannot explain to you, obviously. I’d just add that the way these shells are built I wouldn’t think that anyone would have much of a problem with fit. 

Drivability / Pairings 

Sensitivity 

In Letshuoer’s promotional material for the S12 Ultra, they list this set with an impedance of around 16 ohms and a sensitivity of about 101 db’s. Now, this means that the S12 Ultra can be fairly sensitive. For instance, I used the DT01 dongle dac and I had to go past 80/100 for a sufficient volume level. Other sets rated 16 ohms with higher sensitivity needed far less for the same volume levels. Off of regular Android smartphones with a 3.5 single ended port, the S12 Ultra sounded nice. Granted, you can tell it’s wanting more juice. Also, let’s not kid ourselves, this is a planar, and planars want, yearn for, and desire… some JUICE! Yes, you can listen with weaker sources, but I would try to compel you to get yourself at least a marginally powerful dongle dac. At least 100 mW @ 16 ohms… at least. I used the S12 Ultra with every weak source I had, and the takeaway is the same with each. That is, I wanted to upgrade to a more powerful source. Not that you cannot listen with weaker sources either as the S12 Ultra sounds fine. However, you aren’t getting the most out of this set. 

Scalability 

I didn’t spend much time with weaker sources simply because I know that planar magnetic drivers typically play better with power. Again, a simple $40-$50 dongle dac will suffice. You don’t need some $2k desktop setup. Just something with some good juice. One thing which becomes apparent very quickly is the dynamics of your session when listening to the S12 Ultra with a more powerful source. The treble is more pronounced, the bass is tightened up, the timbre is better, and the stage grows in size and depth. Without question this set wants more power and will reward your listening experience when you provide it. I used so many sources with this review and many of them had plenty of power to bring the S12 Ultra up to good dynamics. Of course, my more powerful daps and dac/amps gave me the best listen of all. Again, try to find a source with solid clean power and the S12 Ultra will show you how well it scales with that power. 

Source Pairing 

This is a very subjective thing to talk about. That is, tonal Pairings with the S12 Ultra. So, the S12 Ultra has what I’d call a warm/neutral take on the spectrum and usually sounds best with anything from warm/neutral to neutral. Even neutral/bright sources do well with this set. Or colder sources. Whatever you want to call them. I find that anything close to or resembling a neutral source sound counteract the warmth of the S12 Ultra very well. That said, if you are a warm lover then maybe you want a warmer source. However, for this guy I like something in that warm/neutral to neutral range. It may be different for everyone though. 

Sound Impressions

*Note: before I dive headfirst into the sound of the Letshuoer S12 Ultra, I first need to jot down some notes concerning my time with this set. First off, I did burn-in the S12 Ultra for about five full days. Now, did this help? EH, maybe a hair. Not a huge difference. Of course, there wasn’t a whole lot I needed changed. The sound out-of-the-box is actually quite nice. Next, I did tip roll to Dunu S&S eartips for my entire critical listening. Also, my Android music player of choice is almost always UAPP (USB Audio Player Pro) as well as Hiby Music / Eddict Player (for a few of my daps). Lastly, I listen mainly to flac or better files (some MP3) which are stored on my devices and rarely stream my music. 

A new planar set… already? 

I have to admit, the Letshuoer S12 2024 Edition is my favorite planar magnetic set available on the market. There are others which are also right up there like the Kiwi Ears Aether (Aether Review) as well as the Letshuoer S15 (S15 Review). However, the point of me saying that is because I really did wonder what in the world Letshuoer was going to do to top the S12 2024! Only a mere year after its release! Well, I got my answer, sort of. Letshuoer didn’t necessarily make a “better” sounding set, they made an equally well tuned set, yet they tuned it ever-so-slightly… different. Almost as though Letshuoer knew they found the golden ratio for planar magnetic earphones and simply tried to tweak some things. They possibly added different damping material around the driver, switched up the venting and airflow tuning. It appears that there has been additional nozzle filter mesh applied. I cannot say for certain, as I didn’t tear this set apart (I like it too much), but there are certainly some differences. Now, this review is not going to be a commentary on how the S12 Ultra compares to the S12 2024. However, I’m simply trying to speak on what my thoughts were going into this review. 

What’s it sound like? 

The Letshuoer S12 Ultra absolutely bucks the planar trend of having that planar timbre. Once again Letshuoer made the magic happen and crafted a planar iem which trades timbre blows with even some of the better dynamic driver earphones. Basically, the Letshuoer S12 Ultra has some nice organic timbre. In truth, the S12 Ultra almost sounds like a cross between a planar and a DD. Now, if I were to call this set anything, I’d say it is a mix between a slightly V-shaped iem as well as a U-shaped tonal color. I cannot agree with myself on either. Why do I say this? Well, because there is a definite lift in the bass region and a slight lift in the treble, while the midrange isn’t as recessed as earlier models in the series. If anything, I’d say it’s a U-leaning sound. Though, I’m still not thrilled with that assessment. At any rate, the sound is what I’d call a warm/neutral sounding set with a tilt towards the warm. I’d also say that the S12 Ultra comes across organic with a smoother and richer take on the spectrum. Definitely leaning more towards musical-over-analytical with what I’d call a 70/30 split. The awesome thing about this set is that it retains the faster transients and immediacy of a fast driver yet with the tonal complexion of a smooth musical iem. It’s really quite nice. Of course, like anything, the S12 Ultra will obviously not fit everyone’s perfect ideal sound. 

Technical Prowess

Of course, any analytical head is not going to enjoy a set with a 70/30 musical/analytical split. You see, the S12 Ultra definitely has a nicely weighted body to its notes. Nothing weak or frail here folks. Now, note weight is substantial, but without sounding so thick & juicy that notes sound blended or too mashed together. It actually rides a fairly fine line. In fact, sound like this would’ve been a lot more expensive only a few years ago, which is wild to think about. I hear nice detail retrieval for the tuning as well as decent instrument separation. Imaging is spot on, and the stage is not just a 2D flat plane of sound in front of me. There’s some depth to this sound as well as solid dimensionality across the board. The S12 series in general is a perfect testament to how far planar magnetic earphones have come. 

Doing pretty good… 

Really folks, the S12 Ultra is simply another high-quality tuning for a thriving driver tech in a loaded world of iems. However, with such a saturated market it is quite something to see a planar set performing so well. I think the one thing which has changed the most since the OG S12, S12 Pro, and Z12 has to be the taming of the treble and the deeper sublevel extension as well as a much less fatiguing display of the spectrum. Much closer to the S12 2024. In fact, I’d say that the S12 Ultra is almost treble-dark. I did say almost. Also, the S12 Ultra “almost” has a nice balance of the mix. No doubt the sub bass region declares the slight majority-share of dominance and the upper mids also share a spot next to the bass to a degree as well. In the end, it has a wholly non-offensive sound that has some very good dynamics for a warmer tonality. Words which come to mind and best describe the S12 Ultra to my ears are rhythmical, fluid, groovy, clean, tight, and musical. In no particular order. Honestly folks, for what the tuning is, there really aren’t any issues that pop out at me other than tonal subjective gripes that some users may have. I suppose the one issue that could be considered a head scratcher is how close the S12 Ultra sounds next to the S12 2024 Edition. If that’s the worst of its issues, then the S12 Ultra is doing pretty good. Let’s check out each 3rd of the mix… 

Bass Region 

The lows on the S12 Ultra are definitely one of the stars of the show here. Without question it has what I’d consider a boosted bass which has prevalence in the sublevels. This is a fairly hard hitting and fun region that easily shows up on any track which even hints at some bass activity. Furthermore, this is the type of bass which most certainly warms the rest of the mix with definite richness provided from that warmth. It’s really a very easy-going signature and the bass kind of gives that easy-going signature a boost of fun. Some deeply extended and hearty meat to go with the organic timbre. I’d also say that the S12 Ultra’s bass region is very clean for being more emphasized. Not to the cleanliness level of some more clinical sounding sets, but clean. You don’t have that layer of warm fuzz veiling bass region notes. Attack is rather hard-lined, tight and impactful while decay is pretty rapid. I like that punchy style. However, in the same breath, this isn’t the type of low-end which will oversaturate the mix in that warmth. Sure, you’ll hear some masking on bass heavy tracks, and you’ll hear those bigger and more bulbous notes come across big and bulbous, but you won’t hear any slow-sludge mud and veil. Furthermore, for a planar magnetic earphone, I find the bass to have good depth, and a solid timbre. Very close to a DD style, but quicker and more agile. I think Letshuoer did a great job once again. 

Sub-Bass 

The sublevels of the bass have plenty of weighted rumble and guttural low droning haptic feel to any track which displays such a thing. This is one thing that really drew me to this set. It has that clean sublevel rumble followed quickly by a heavy and robust slam. Bass guitar has all the feels as well. You hear and feel plenty of juddering growl, but also a rich harmonic structure. The sublevels almost have layers which press beyond simply sounding rumbly. I hear the natural overtones of the bass guitar in “Ramble On” by Led Zeppelin coming through rather well, yet they do come across a bit tighter than something like a DD would sound. Also, the heavy and fast paced riff from “Hysteria” by Muse is another which shows off not just the tonal aspects, but the speed as well. The S12 Ultra hits every note in stride, easy-peasy. However, it’s really any bassline, bass drop, vocalist, or any other sound which trends around the sublevels that are replayed pretty well. Obviously, not everyone wants or yearns for a heavier and warmer bass. That said, the S12 Ultra’s sub-bass isn’t just about sounding bullish. In truth, the sub-bass serves the whole of any composition nicely providing a solid and dense foundation which (in my opinion) allows the listener to hear every track without the distraction. Also, the sub-bass weaves itself into most tracks independent from the rest of the mix rather nicely as well. 

Mid-Bass 

I think the most enticing characteristic of the S12 Ultra’s mid-bass lies in its ability to provide a nicely defined sound allowing me to hear the nuances in a bassline. Having said that, I’d say that the mid-bass floats right around moderate in emphasis. Nevertheless, it is plenty large enough to sound full bodied and very clean. Furthermore, this is a speedy mid-bass which doesn’t get easily tripped up. Also, I hear just enough bass bleed into the mids. A very tasteful amount. Just enough to give the midrange some body, some warmth, yet without losing very much clarity. So, it’s a very nicely done bass. Like I said earlier, the bass comes across very similar to a DD yet with the speed and precision of a planar. It has a controlled impact. Nothing loose or sloppy and nothing comes across as a one-noted mishmash of bass. I am definitely liking what I’m hearing. I will say, the mid-bass isn’t quite as forward as the S12 2024 and isn’t quite as impactful with a touch less presence in the mix, but it is slightly better defined to my ears. Even with its less “emphasized” mid-bass boom, it still definitely has a very controlled-resonant and full-bodied character, remaining defined and well-structured while never really sounding bloated. It’s a nice mid-bass folks. No it isn’t going to make bassheads perfectly happy, but it’s a high-quality bass with the depth and fullness of a DD as well as plenty of speed for more complex and nuanced tracks. 

Downsides to the Bass Region 

I think the number one issue that some folks will have with the S12 Ultra is that the mid-bass doesn’t have that forward and profuse slam that some may like. Most certainly I don’t think I’ll find any bassheads scratching and clawing to get their hands on this set. The S12 Ultra’s bass region is a quality-over-quantity style, yet without that much lack of quantity. Especially with the deep and rumbly sublevels. This is a clean bass, very fast, able to handle reasonably complicated tracks with relative ease as well, but it won’t keep the big bass lovers happy. The only other aspect of this bass which may not be to everyone’s liking is that it may actually be too emphasized. Without a doubt there are tracks where I will hear some masking occurring due to the prominent sub-bass rumble or the boom of a bigger bassline. The S12 Ultra’s low-end has a measured bleed into the midrange but not everyone enjoys the bass mixing it to the mids. In fact, many folks desire no bleed at all. Like anything in this hobby the S12 Ultra won’t make everyone happy, but I think the majority of listeners would appreciate this bass response. Honestly, that’s about it folks. Letshuoer did a great job with this one. 

Midrange

In my opinion the midrange is easy going. This is not some ultra exciting and aggressive midrange, but one of smooth curves, fluid and totally groovy. As I said earlier, the overall tone of the S12 Ultra is certainly one of warmth, one of richness, and one which champions musicality-first. I say that but the S12 Ultra is actually very nice in its technical ability as well. However, I digress, what the S12 Ultra’s midrange represents is a melodic wave-like journey. Okay, that’s going a hair too far, but it is wave-like, it is very melodic too. In fact, the midrange may be its best quality. Sure, the bass region is great, but it’s the midrange which truly makes this set shine. Having said that, I don’t feel that the S12 Ultra is mid-centric, or vocal-centric, and I don’t even feel that the midrange is pushed too very far forward. It fits perfectly actually. Nothing too recessed, yet nothing which comes across as dominant in this range either. What makes this midrange nice is its harmonious atmosphere, the way the mids melt into the music, and the rich authoritative body that those midrange notes flow with. Furthermore, there isn’t an aggressive part of this midrange, no shout, no pierce, no sibilance, and no planar timbre either. Really, the midrange is a testament to the skills of Letshuoer’s experienced people. In fact, the only sign that the S12 Ultra uses a planar magnetic driver is in its driver speed alone, because tonally, this set sounds like a dynamic driver earphone. 

A nice midrange 

Anyways, the midrange is silky smooth yet comes with tight and controlled dynamics which are toned down just a hair. This helps to bring upon a relaxing take on the spectrum. In truth, the midrange of the S12 Ultra sounds like Letshuoer just kept polishing, and polishing, and polishing, until there wasn’t a jagged, edgy, or sharp spot in its tuning. Effortlessly smooth, silky and refined, just warm enough to add some weight, just bodied enough to sound substantial, and just dynamic enough to help those rich notes come across bold. This isn’t to say the S12 Ultra lacks energy either. It’s just not “energetic” in character. Its energy is reserved, refined, controlled, and never oversaturates the cadence or over-stimulates the spectrum. I happen to like its dynamism. The impressive part is how the S12 Ultra portrays that energy. What I mean is that the S12 Ultra’s midrange doesn’t lack proper edge detail in instrumentation. Snap for percussion, subtle abrasiveness and bite on strings etc. Obviously, there is enough treble infusion to go with that bass warmth and body creating this nicely made midrange cocktail. I really do enjoy what Letshuoer created here folks. Very much similar to the S12 2024 tonally, but more balanced, and more traditionally “organic” as well, among other small differences (for the record, I am NOT saying one is better than the other… moving on…). 

Lower-Midrange 

The lower midrange has that nice body to this range brought on by the added I fusion of subtle warmth provided from the bass region. Like I stated earlier, I feel that the bass bleed into this range is just about perfect. Not too much that the low-mids sound blunted and boring, and not too little that notes come across thin, frail and weak. This is the range that most male vocalists reside in and I can say for sure that the S12 Ultra does a very solid job of helping males to have a certain vibrant yet totally authentic sound. Not to mention again… the low-mids have some great note body. In fact, it’s the note body which gives male vocalists that authoritative bravado, that masculine edge, that robust weight. To an extent. Males like David Draimen of Disturbed wonderfully and masterfully songs “The Sound of Silence” and folks let me just say that the S12 Ultra does an equally masterful job of presenting his masterful voice. Whether those smoothly flowing and golden harmonic verses within this track, or David’s grungy, deep, guttural and bullish tones the S12 Ultra places those vocals subtly out front, with good presence, and with a spritz of vibrance. He sounds awesome. I have so many notes’ folks, so many. In fact, I have exactly 17 male lead songs (within my notes) in which some form of the words “awesome” and “wow” were expressed. Now, I’m not saying the S12 Ultra is the best there is. I’m not even saying that it’s my favorite in the price point. But I am saying that while I sat soaking in my music, I really enjoyed how the S12 Ultra portrayed those male vocalists. 

Upper-Midrange 

The upper midrange comes across more forward, more energetic, livelier, and more vibrant than the lower midrange without coming across aggressive at all. Just more-so than the low-mids. If the low-mids are where males reside then it’s the upper mids where females reside. What I like about the S12 Ultra is that female vocalists have that moist vibrance to them. I love that there is not a dry note on this set. Another thing that I found was that the S12 Ultra has a wonderful ability to render emotion from a track. I also really enjoy the warm clarity in this range. Resolution is very high for this type of tuning. Notice I said… “for this type of tuning”. The S12 Ultra has very nice clarity for a warmer sound. This is not always the case folks. I mean, nothing sounds blended, notes have separation, transients are clean and tight, and every note has a smooth-like-glass lining. Nothing comes across grainy, fuzzy, and I don’t hear any straight-up planar style timbre. Nothing metallic. Also, everything in this range has a smooth and even texture with a bodied expression. The S12 Ultra’s upper mids present the spectrum in a way that brings those brighter hues right to the point of glare and then evens those harsh tones out with a polished and refined brilliance that melts right into the warmer midrange tonality. Females benefit so much from this! 

Females

If the lower midrange is awesome for male vocalists for this warmer tuning, then females are spectacular. Of course, you have to enjoy a less aggressive sound. However, the S12 Ultra’s upper-mids have a subtle warmth, some fullness, and some vibrance, but they also have just enough air as well. At any rate, females like Caitlyn Smith in the track “High” come across so well defined, with such a forward and prominent sound, yet without ever crossing that sharp line. Her voice goes from soft and flowery, sweet and gentle, to resounding and powerful. To add to that, most sets cannot resolve this chorus well as there’s usually too much going on. However, the S12 Ultra does a very good job separating instruments and Caitlyn’s strong voice. I really enjoy how the upper midrange has a very natural sound as its timbre is very much organic. The track “I Can Change” by Lake Street Dive is such a soothing sweet melody. I can hear as the S12 Ultra literally squeezes out actual emotion from this Rachael Price‘s vocals. Hope, empowerment, reflection, are sung in a soft but yet powerful and cathartic way and the S12 Ultra really does give her voice a canvas. Folks, I realize that many sets can perform this. The S12 Ultra is not on an island in its ability. Shoot, there are probably better sets at performing female vocals at lesser prices. The point is that male and female vocals are certainly a strong suit. A strong suit amongst many other strong qualities. Females sound great. 

Instruments 

I should very quickly go through some instruments and how they come across. Some good points as well as some possibly not-so-good points (depending on your preferences). I think we can all attest (anyone who’s heard the S12 Ultra) that this set prioritizes natural tonal elements, musicality, and a pleasant-engaging experience over precision and clinical details. Most percussive instruments sound full, robust, and weighted with that snap needed on attack. Piano, cello, and even acoustic guitars carry a more full-bodied sound, with a vibrant texture to them. The nuances aren’t lost on this set either as the planar driver has the inherent speed and transient swiftness to articulate subtleties in a clear way, most of the time. Most brass instruments have that sonorous quality, with preserved clarity and never sound harsh to my ears. So, there’s many instruments which benefit from this tuning. Though, I did notice some woodwind instruments that may come across a hair less lustrous and energetic, perhaps too warm. Maybe a bit too reserved. Another is orchestral style strings which I feel lack a slight bit of brilliance as well. Granted, this is not a rebuke of this set. Not by any stretch of the imagination. I’m just trying to point out some good stuff and some subjective “possible” issues. Anyways, it’s almost pointless describing instruments as every track replays them differently and all instrumental points are just broad generalities. So, I won’t go any further with that. 

Downsides to the Midrange 

The largest downside to this midrange would be a subjective issue coming from those who really don’t enjoy a warmer, smoother, and richer style midrange. I too want something with a hair more energy at times. Shoot, I just got done reviewing the Kinera Thorking which is damn near bright at times and I loved it. However, I love to come back to an organic sound. That is what the S12 Ultra is. Sure, it may lack some pep, some energetic bite, some vivacity, but the S12 Ultra makes up for that with its clarity, speed, and natural timbre. So, to say it in another way; analytical heads are not going to enjoy this set. Nobody who values something dry, clinical, and brilliant is going to enjoy the S12 Ultra’s warm, moist, and less energetic sound. I think Letshuoer once again nailed the planar sound and the S12 Ultra perfectly embodies just how far they have come since the original S12. It’s quite remarkable. 

Treble Region 

One thing that the older S12 series models had a lot of was treble shine. They were known for that. It was the biggest gripe by far of those older sets. I got to review and listen for myself as Letshuoer went through the tuning journey with sets like the S12 Pro, the S15, the S08, the S12 2024, and finally to the S12 Ultra. I saw the progression from bright and tinny, to smooth and warm-ish. Those older sets had some aggressive highs, forceful in those brighter inflections, yet were very well detailed and airy. What the S12 Ultra does is it balances out the spectrum much better. Gone are the screaming highs and in comes a more refined and more quality treble. Albeit less intense. The highs on this set have adequate brilliance, just enough crispness, and decent extension. I wouldn’t call this treble “laid-back”, but I also wouldn’t call it bright. Definitely a more musical take on the treble keeping a more rhythmical and fluid style with better note body, whilst not missing out on stuff like detail retrieval, note separation, treble bite, and subtle air. 

Technicals

One thing which seems to defy normal logic in the audio space is when a warmer and less intense treble actually has some good technical ability. The S12 Ultra embodies this as micro-details come through fairly well without the need for that offensive and hot forced-resolution that so many iems carry. The S12 Ultra lives off of its good drivers, smart tuning, and balance. Once again, this set has great clarity for a warmer set. So much of that has to do with the quality of the S12 Ultra’s treble. Again, just enough air, hard-tight attack followed by a quicker decay-sustain, nice wide and decently airy stage, and some good ole’ solid resolution. The treble has nice note separation on this set, and notes aren’t just blunted and smoothened over. Notes have some edge to them, some etching around them, and notes in the treble do have some bite. Again, the S12 Ultra’s treble has adequate brilliance, adequate crispness, and just enough radiance to uplift, create space as well as present both macro and micro details in a coherent and reasonably distinct way for the tuning. Again… for the tuning.

Speed

One of the best qualities of a planar magnetic driver is its speedy and tight nature. There are very few drivers which can perform as well as a planar in this regard. Even when tuned warmer, smoother, and juicier a planar can still stop and go on a dime with that hard and tight fast-twitch reflex. As far as the S12 Ultra, it can easily replay some pretty complex tracks without missing much, and it can do so in a pretty clear way. For example, take any Billy Strings track. How about “Ice Bridges”. Friends, those jet fast mandolin notes coupled with the breakneck speed of the guitar and banjo sound fantastic on this set. Every note has its own space. I can hear each note start and stop as each note has a decently articulated beginning and end. Or “Chocolate Chip Trip” by Tool which has some very complex and even chaotic percussive elements. You’ll hear rapid fire treble notes and the S12 Ultra seems to do very well. Sure, it won’t top some sets which are born and bred for fast precision. But for a musicality-first iem the S12 Ultra does a fantastic job. This is a speedy treble when it needs to be, when a track calls for it. Also, it is a very musical and polished treble as well. 

Extension 

Also, I want to quickly speak on the nice upper treble extension found on the Letshuoer S12 Ultra. Now, please don’t confuse what I’m about to say. I don’t think the S12 Ultra is some treble masterclass set. Put all of my words in context please. For a “warm” “smooth” and “musical” iem the S12 Ultra from Letshuoer does a fine job at presenting a solid treble. Okay, so, the upper treble extension is actually quite good. To my ears the S12 Ultra was tuned in a slightly toned-down manner yet it can easily display info past 10k. However, it does so with none of that smearing style treble splash. This isn’t the easiest or most fun thing to listen for, trust me on that. Yet it is very apparent that Letshuoer did a great job in this area when I listen to some other similarly priced iems. I usually bring up stuff like the secondary harmonics of a cymbal strike simply because so many tracks feature cymbals & hi hats. What I found was that generally if a recording is good enough, I hear very clean harmonics with good volume and presence. No smearing of treble tizz fading off into the nether regions of sound. There’s some chime, some radiance to those notes, they have at least some prominence. That’s not all. Another nice quality of this toned-down treble with nice extension is the openness that it provides. The extension on this set does stretch the stage, aids in note separation, and it brings some dimensionality to the overall sound. Anyways, I thought that was worth speaking on. 

Downsides to the Treble Region 

Now that you’ve read my “mostly glowing” words about this musical style treble, I would be remiss if I didn’t also speak on some less awesome qualities for those who desire an even better and more sprightly treble. Without question there are so many friends and other hobbyists who greatly desire a shining and brilliant treble which is full of lustrous tones, airiness, and loads of sparkle. Some of you guys and gals only want that. I just want to level with you, the Letshuoer S12 Ultra will definitely disappoint those people. Treble heads and even moderate treble lovers will find this treble lacking. As good as it is in detail retrieval (for the tuning), it is not going to eclipse some brighter and analytical style tunings around the $150-$200 price point. There are a few sets which absolutely slay in this region, tuned for treble, and made to resolve everything and anything. Yes, the S12 Ultra is good and yes, it’ll surprise some people, but it won’t intrigue those treble bois amongst us. 

Technicalities 

Soundstage 

If I were to say anything about the Letshuoer S12 Ultra’s soundstage, I’d say it’s about what I’d call average in size, pretty intimate, yet not congested. I hear about average width and height, but I hear nice depth of field for a planar set. It should be no surprise that most planar iems seem to not always carry the best depth of field. We’ve seen many fantastic planar sets which simply don’t have the best front to back representation of the sound field. However, this also happens to be one huge difference between Letshuoer planars, and other planars (not named Hidizs MP145 or Kiwi Ears Aether). The S12 Ultra has some very nice layering abilities. Not the best in the market at this price point, but very nice. Basically, the S12 Ultra doesn’t sound like a 2D flat plane of sound in front of me. Now, the stage is also somewhat intimate, yet in the exact same breath it’s also very full. The soundstage fills almost the entirety of my mind space, but it’s closer to the listener. So don’t expect some enormous and grand stadium of sound but do expect a well dimensioned and nicely proportioned stage with solid separation and well-done layers. 

Separation / Imaging 

As far as sound separation, the S12 Ultra does well for a warmer and smoother iem. I think its saving grace is the slightly tighter transients and good clarity. Note separation is very nice to my ears though it will not compete with sets which are tuned for it. I mean, no doubt the S12 Ultra isn’t going to be a top class set in this regard. Nor should we expect it to be. In my opinion, note separation, Imaging, and even detail retrieval is all simply bonuses from having the planar driver tech. Basically, note separation is definitely “good” without being “great”. Also, I would never want to screw up the musical nature of this set so that there is more air and separation between notes. I like it just as it is. Imaging on the other hand is actually very nice. I never have an issue spotting or placing instruments and all vocals are right in the center (depending on the track). The only time that imaging and separation seems to struggle or not sound as distinct is when you have a heavy bass track and the bass is masking those frequencies, if you ask me. All in all, separation and imaging are definitely very solid attributes of this melodic and wholly musical iem. 

Detail Retrieval 

You can take everything I just said in “Separation / Imaging” and apply it to the detail retrieval because it walks the exact same line. Honestly, detail retrieval is very solid. Details are easy to discern. Both macro and micro come through relatively well considering the tuning. Having said that, this set was not created to bring the subtleties to the surface. Again, this isn’t some dry, ultra-airy, analytically tuned iem. This set is musical at heart. Granted, the S12 Ultra does have some sprightly transients, good clarity, nice resolution, the stage is decently sized, and there is a moderate level of air/openness as well. These traits make hearing details fairly easy. So, definitely not tops in class, and there are definitely better iems at detail retrieval, but the S12 Ultra does a fine job. 

Comparisons

Kiwi Ears Aether  ($169)

Let’s start this comparison off with one of my absolute favorite planar sets of the last few years with the Kiwi Ears Aether (Aether Review). This is a set which took me by surprise folks. In no way was I prepared for Kiwi Ears to bust out this absolutely awesome sounding planar set. Instantly the Aether outperformed many planars under $300 and was universally praised. I gave it a raving review. Now, the Aether comes equipped with a 15.3 mm planar magnetic driver and is tuned by some of the best in the business. Let’s see how these two iems differ. 

Differences 

To begin, the Kiwi Ears Aether is a much larger set of iems. There is quite a big difference as the S12 Ultra is smaller, and lighter too. In fact, small ears beware as the Aether is quite large. Also, the S12 Ultra is made a bit better, more durable, more substantial too using aluminum rather than the Aether’s 3D printed resin. Granted, neither set is badly built. Both iems look awesome. I happen to prefer the S12 Ultra as it is simpler, and less flashy. But the Aether is flat out slick looking, and I don’t want to take away a thing from it. As far as unboxing experience goes, the S12 Ultra comes with a better case, much better modular cable (not even close!!), and better eartips. So basically, the S12 Ultra has a much better accessory haul. Both sets cost the consumer $169 and so they are the exact same price. 

Sound Differences 

This is a comparison with two sets that have very similar frequency graph charts but they sound a bit different in real world listening. Without question this comparison is a preference battle. They graph close, but they don’t sound all that close. For starters, the S12 Ultra is a warmer and more dark flavored sound, smoother, more organic in timbre. The Aether comes across slightly brighter, closer to neutral, more technical while the S12 Ultra is more musically gifted. The bass of the S12 Ultra is deeper, better extension into the sublevels, while the Aether is more snappy, with a more rapid release punch to it. Perhaps the S12 Ultra’s bass is a tad slower (which isn’t a bad thing). The mids of the S12 Ultra are silkier, more organic, better note weight, while the Aether is closer to neutral, cleaner, better resolution, and more detailed and airy. Next, the treble of the Aether is more sprightly, more brilliant, more crisp, but both sets carry good extension. However, the S12 Ultra has more of a natural hue to the treble with better note body, smoother across the board, and it has a less offensive sound up top. Of course, neither set is what I’d call “offensive”. The Aether carries slightly better detail retrieval across the mix, better note separation, while imaging is about the same on both sets. As far as the soundstage, the S12 Ultra has more depth, more of a dimensional feel to its stage while the Aether’s stage is a bit wider in presentation. 

Final thoughts on this comparison 

Friends, these are two of the behemoth planar magnetic earphones under $200. Good luck finding flat-out better planar iems. The S12 Ultra and the Aether both outperformed my expectations with quality build, design, and tuning in both sets. There are moments where the Aether is exactly what I want in my ears. Trust me it happens often. Though, if I had to choose between the two I’d go with the S12 Ultra. That organic smooth character is just too juicy. However, you may be totally different. Hence why I called this a “preference battle”. Again, two solid performers with different sound characters. 

Letshuoer S12 2024 Edition  ($199)

If ever I had a favorite planar magnetic earphone, it’d be the S12 2024. Of course, the S12 Ultra has a few things to say about that. I actually reviewed the S12 2024 (S12 2024 Edition Review) earlier this year and I enjoyed its sound right away. Now, the S12 2024 has the exact same driver as the S12 Ultra yet with slightly different acoustic structure surrounding that driver. Instantly the S12 2024 was what I’d consider a beloved iem. I like to say that it was the S12 2024 that Letshuoer perfected its planar timbre. Or at least came very close to it. Let’s check out some of the differences… 

Differences 

To start, both sets are identical in their overall footprint measuring darn near identical size and style. However, the S12 2024 is made using titanium alloy which is a bit heavier and more substantial than the aluminum alloy of the S12 Ultra. Next, the unboxing for the S12 2024 is more luxurious. Which stands to reason being that it is a limited-edition set. Now, the S12 Ultra does come with the Letshuoer DT01 dongle. So there really aren’t many differences at all between the two as they both have the famous S12 series build, same style, and both look seriously dope. The last difference would be in price as the S12 Ultra is $30 less expensive at $169 while the S12 2024 comes in at $199.

Sound Differences 

The difference between the two of these sets is very small. I mean, they are very similar. The S12 Ultra basically built upon what Letshuoer did with the S12 2024. The S12 Ultra comes across slightly smoother, warmer and darker sounding. As far as the bass goes, the S12 Ultra has a deeper and more authoritative sub-bass, but a less impactful mid-bass. I found the S12 2024 simply has a ever-so-slightly bigger bass section which sounds more forward, better presence, but not as defined as the S12 Ultra. The midrange of the S12 Ultra is warmer, smoother, less vibrant, and actually has about the same note body to my ears. The S12 2024 has that extra lift of energy whilst keeping a bit more of a correct and less colored timbre by a very small degree. The treble of the S12 2024 is more crisp, exciting, and has better overall resolution. Though, the S12 Ultra keeps a slightly more fluid treble, better note body, and while it doesn’t have as crisp of a sound, it still has plenty of brilliance to cover this area of the mix. To my ears the S12 2024 has slightly better detail retrieval as it isn’t as dark and has a touch more upper treble lift and air. Note separation is close on both sets, as is imaging. I find the stage of both sets to be similar as well. They both have a solid stage with good dimensionality. 

Final thoughts on this comparison 

In truth, I have grown to really enjoy both sets. Personally, I like the S12 2024 a hair better because it has just a touch more vibrance and a more impactful mid-bass, but I really enjoy both sets. Of course, that could change tomorrow depending on my mood. Both sets are 1 and 1A of some of the best musicality-first planar magnetic earphones on the market under $300. Without question folks. These are two fine sets. Take your pick and you cannot lose. 

Final thoughts on the Letshuoer S12 Ultra 

What can I say, Letshuoer once again comes out with a phenomenal iem that instantly lands itself near the “tops in class” for planar magnetic earphones under $200. When I was asked to review this set, I did have some hesitation. Not that I didn’t want to hear them as I want to hear every iem on planet earth. But I simply didn’t know where Letshuoer would go with this tuning. Again, how was Letshuoer going to top the S12 2024 Edition?! Come to find out they weren’t trying to “top” anything at all. Instead Letshuoer made something very similar with only a few distinct enough changes to qualify this set for the market. I am so very happy that Letshuoer went this route with the last S12 series iem. 

End of an era

Anyways, this truly is the “end of an era” folks. One of the most successful series that we’ve ever seen in this hobby. The S12 series has planted itself in the legendary range. To think that we will never again see another S12 iem makes this last review a bit of a bittersweet moment for the community. Having said that, I cannot wait to see what Letshuoer comes up with next. In my most honest thoughts, to me the S12 Ultra is a calm evolution of this series. It’s a certain refinement of all that Letshuoer has learned through years of sharpening this series, brought forth from community opinion and market trends. This is something that the good brands do well. They listen, they pay attention, and they perfect the product that they put their name on. Never will a truly great brand produce product after product like an assembly line.  At any rate, it is a comforting thought for anyone looking to purchase a planar set under $200 that Letshuoer has done their homework, learned from experience, and brought this driver and this series to its pinnacle. I can tell you with 100% conviction that if you enjoy that warm-ish musical style that has a rumbly bass and a nice technical ability then the Letshuoer S12 Ultra is without question a very solid purchase. 

The Why… 

Because, my word folks, Letshuoer has gone through the paces with all of their planar iems. You already know you are getting a set which has been refined over years of R&D and experiential knowledge. However, just look at this set. I really have always enjoyed the appearance of this series and the S12 Ultra follows right in line with all of those S12 series iems of yesteryear. Also, that mocha brown is so dope looking! The S12 Ultra comes with solid accessories which don’t force you to tip roll or cable swap. You even get a 3.5 dongle dac as well. The build is great with its all-aluminum chassis and it’s really just a very good package altogether. 

That sound… 

However, it’s the sound which makes this set worth every penny of the $169 that Letshuoer is asking. That clean warmth is so very engaging folks. The bullish sublevel bass, yet the clean and tight mid-bass slam. It comes with tight transients that attack on a dime and decay a hair faster than natural. The timbre is also very close to natural, slightly colored from the emphasis down low, but organic, earthy, and fun. Nothing about this iem is offensive yet it has plenty of toned-down energy and vibrant enough dynamics. The vocals on this set are great too with a semi-forward midrange and an ability to render instruments very well. The S12 Ultra is also very capable technically as note separation, Imaging, layering, and detail retrieval are all above average. Which is saying a lot for such a smooth sounding iem. It’s simply refined folks. I know I’ve said that a lot. In truth, there aren’t many other words which describe the S12 Ultra’s sound better. Also, the soundstage has depth, it has a 3D style atmosphere within a very full yet intimate stage. Friends, if you enjoy what I just described then the S12 Ultra is a no brainer at $169. This set is an easy rec from me. 

Conclusion 

To conclude my full review and feature of the Letshuoer S12 Ultra, I have to Thank the good folks over at Letshuoer for providing this set for review. No doubt about it Letshuoer is doing some great things in the personal audio space and I’m happy to report on some of those things. So, thank you very much. As always, I also have to thank you, the reader, for checking out this review and spending your precious time here. It’s because of you that we survive and it’s because of you that mobileaudiophile.com thrives as well as it has. I hope to continue to gain your trust for years to come. 

Other Perspectives 

Another thing that I will always do is implore you to check out other thoughts. Get a collective idea about a product. Hear other testers, listen to other community members, take in other opinions. We all know that this hobby is the most subjective hobby on earth (one of them anyways) and each of us are different. No two people are perfectly alike. It’s true in life and it’s true in the audio hobby. So please, get other perspectives and hopefully you will figure out the perfect iem to suit your ideal sound. Beyond that, I’m done folks. So, take good care, stay as safe as possible and always… God Bless!!