Questyle M18i Review thanks to Questyle
I’ve spent time with more portable DAC/amp combos and dongles than I can count—some were exciting, some forgettable, and a few genuinely special. The Questyle M18i isn’t just trying to be another dongle or a shrunken DAP. It’s playing a different game. Somewhere between the ultra-portable dongle and the full-function desktop setup, this little device manages to punch above its weight in ways that genuinely surprised me.
Let’s get into what it actually is, what it does differently, and why it deserves attention.
What’s Under the Hood?
At its core, the M18i features two ESS ES9219Q DAC chips, each configured in mono. Running DACs in mono (one chip per channel) isn’t just marketing—it actually helps improve channel separation and clarity. Especially when paired with precise amplification, you start to notice instruments living in their own space instead of blurring into one another.
Speaking of amplification, this is where Questyle really leans into its unique identity. Instead of the usual op-amp configuration you’ll find in most dongles, the M18i uses Current Mode Amplification (CMA)—something they’ve developed and refined over several product generations. Inside this tiny housing are two CMA SiP modules, each housing two amplification engines, making it four total CMA circuits. It’s not about brute force—this is finesse. It’s like using a scalpel instead of a hammer.
The result? A distortion rate so low it’s practically inaudible—around 0.0002%. What you hear is a shockingly clean, open, and balanced sound, regardless of genre or gear.
On the digital side, the USB connection is handled by a 16-core XMOS XU316 processor. This is a beast of a controller, far more powerful than what you’d find in typical dongles. It allows for ultra-low latency and stable playback, even with high-res files up to 384kHz/32-bit PCM and DSD256.
And yes, compatibility is basically universal: iOS, Android, Windows 10/11, macOS, HarmonyOS, and even PSP—everything works right out of the box. No fussing, no custom drivers. Just plug and play.
Real Features You Actually Use
Now, let’s get away from the spec sheet. Here’s what the M18i gives you in daily use that actually matters:
- 3.5mm and 4.4mm outputs: Whether you’ve got a classic single-ended setup or a balanced cable on your IEMs or headphones, you’re covered.
- OLED Display: This isn’t just for show. It tells you your bitrate, gain level, battery status, and active input. It’s surprisingly helpful when you’re switching sources or codecs.
- Manual Gain Toggle: There’s a physical switch for gain—not a digital menu, not software-controlled. You feel it, flip it, and instantly give a bit more juice to harder-to-drive gear like the HD600.
- Dual USB-C Ports: One is for data/audio, the other for power. That means you can listen while charging—a feature that most dongles still skip.
- Bluetooth 5.4: And it’s not just basic BT. This supports LDAC, aptX Adaptive, aptX HD, AAC, SBC, and even LE Audio. It’s all managed through Snapdragon Sound, which ensures high-bitrate and low-latency performance—perfect for wireless audiophiles.
- Internal Battery (500mAh): Unlike most dongles that rely on your phone’s juice, this one powers itself in Bluetooth mode. That means less strain on your phone and no heat buildup from USB power draw.
- HD Voice Calls: Thanks to the Qualcomm cVc 8.0 tech and the Infineon MEMS microphone, it even doubles as a top-notch call device. Background noise is filtered, voice clarity is sharp. It’s weirdly satisfying to use this on Zoom calls.
What Makes It Uniquely Questyle?
Here’s the stuff you won’t find in your average dongle:
1. Current Mode Amplification (CMA)
Questyle’s flagship tech. Instead of using traditional voltage-driven amplification, CMA works on current. It’s fast, clean, and massively lowers distortion. In this case, you get four independent CMA engines. That’s rare at this size and price.
2. ESS + XMOS Synergy
These chips weren’t just tossed in—they were carefully matched. The ESS DACs and the XMOS processor are integrated under what Questyle calls their TTA (Triple Decoding Architecture). It’s a fancy name, but the goal is simple: synergy that results in glitch-free, full-resolution playback with zero audible lag.
3. Snapdragon Sound Certification
If you’ve got a compatible phone, this makes a real difference. Wireless never felt this close to wired.
4. Apple MFi Certified
You can connect it directly to iPhones and iPads without adapter headaches. For iOS users, that’s peace of mind.
📏 Design and Everyday Handling
- Chassis: Machined aluminum body with a glass face panel—feels premium, solid, and durable.
- Weight: Around 50g. Just right—not heavy, not too light.
- Buttons: Proper tactile controls. Not touch-sensitive weirdness. You feel them, you know what’s happening.
- Form Factor: Fits in a jeans pocket or clips to a bag. Looks like a mini high-end Walkman without the screen-heavy interface.
It’s the kind of device you want to carry. You trust it won’t fail, and it won’t embarrass you with cheap looks.
⚡ Power Output and Real Performance
The M18i outputs about 28mW into 300 ohms balanced. That might sound modest on paper, but it’s the quality of delivery that matters. With full voltage swing and low noise, it drives planar IEMs like the Letshuoer S12 beautifully. It even pushes a beastly headphone like the AKG K240 600ohm confidently from the 3.5mm port.
Questyle M18i as BT DAC / AMP
While listening to Africa in 24-bit from Qobuz—though converted to AAC on the M18i—I’m hearing a marvelous playback with the S12. Everything feels faithful and organic, capturing all the imperfections and charm of that decades-old recording beautifully.
Again from Qobuz, Russian Circles – Harper Lewis plays at 50/100 volume on my phone, and 40/60 on the M18i, delivering a level of detail I hadn’t heard before. It’s organic, yet smooth. The band clearly values nuance, and on the M18i, it all comes through at a pro level—both musicality and technicality peak here. After listening at the same level for a while, I noticed that 5/10 on the phone translates to about 3/6 on the M18i in terms of perceived loudness.
<So far, there’s zero background hiss>
When Bouree begins, the bass guitar rumbles gently through note changes. After Ian’s breath, the rest of the band joins in, and I can distinguish each member’s presence—like I’m wearing an IEM worth over $300. Everything sounds naturally layered and almost 3D-like.
Finally, Tokyo Kosei Wind Orchestra starts playing and captivates me with my trusty S12. If I went full audiophile mode, I’d feel like I could inspect every instrument, whether in the foreground or background. The sense of openness, paired with a pitch-black background, is just superb.
<Speaking of which, I connect it to my endgame monster to see what it can really do—same track>
Once I hook everything up and start playback under identical output conditions, the first thing I notice is a slight drop in volume. Come on now, that’s a bit unfair, no?
So, without touching the phone, I crank the M18i to 60/60. Immediately, the volume, body, and clarity all improve. Then I also raise the volume from the phone side (75/100), and while the M18i starts gasping for air, it still manages to hold the line gracefully. But let’s not torture it—this much drain isn’t ideal for Bluetooth mode. Pushing the source level even higher ends up causing actual ear pain, even though playback improves. So, yeah—this was the Bluetooth experience. Let’s now look at it as a dongle.
Questyle M18i As Dongle
Source: R4 in Pure Audio Mode. Whiskey in the Jar is the clearest playback I’ve ever heard. I could probably write out the lyrics from what I hear. And Metallica? This is the full-force, thunderous (yet gentle for that county cover) heavy metal we know. No instruments overlap; everything hits with excitement. Especially catching the subtle note shifts in the buried guitar solo of the mix—very rewarding. If I focus, I melt into the music. It doesn’t get more immersive than this.
On We Can Make the World Stop, there’s a cleanliness and separation you wouldn’t expect from electronic music :p. But when the bass kicks in, even the S12 steps up and delivers an unexpectedly powerful performance. The crystal-clear effects that come and go throughout add a lovely layer.
And I wrap things up with GOAT. Using the Questyle M18i as a dongle unleashes all the mastery in the track straight into my ears via the S12. The body thickens when needed, and thins out like silk at just the right moments. I really enjoy this dynamic capacity.
Pros
- Exceptional Sound Quality: Clean, detailed, and natural tonality with excellent dynamic range and separation—especially when paired with S12.
- CMA Amplification: Unique Current Mode Amplifier (CMA) architecture delivers ultra-low distortion (0.0002%) and a transparent, fast sound.
- Dual DAC Architecture: Two ESS ES9219Q chips in mono setup for better channel separation and depth.
- Robust Compatibility: Works seamlessly with iOS, Android, Windows, macOS, HarmonyOS—even PSP.
- High-Res Format Support: Handles PCM up to 384kHz/32-bit and DSD256 with ease.
- Bluetooth 5.4 with Snapdragon Sound: Excellent codec support including LDAC, aptX Adaptive, LE Audio—great for wireless use.
- Dual USB-C Ports: Listen while charging—practical and rare in portable gear.
- OLED Display & Manual Gain: Useful for real-time feedback and tailoring output to your gear.
- Dead Silent Background: Zero hiss even with sensitive IEMs like S12.
- Solid Build Quality: Premium materials, compact yet rugged feel.
❌ Cons
- Bluetooth Output Slightly Limited in Max Power: When pushed hard in wireless mode, it can get slightly breathless at higher volumes.
- Internal Battery Drains Quickly in BT Mode at Max Output: Driving high volumes over LDAC + high gain takes a toll on battery life.
- Not a “pure” DAP: Lacks onboard storage or app interface—strictly a DAC/amp and transport tool.
- No onboard EQ or filters: What you get is neutral and transparent—but no sound tweaking options onboard.
- Pricey for a dongle-style device: For those just looking for a simple USB DAC, it may feel like overkill.
Questyle M18i Review Final Thoughts – A Different Breed
The Questyle M18i doesn’t try to replace your DAP. It doesn’t overload itself with features just for the spec race. Instead, it refines the core experience: top-tier sound, real-world usability, and high compatibility.
This is for people who want desktop-quality audio in their pocket, without diving into Android DAP territory or juggling dongles that either sound flat or eat phone battery for breakfast. It’s clean. It’s fast. It’s thoughtful.
And it’s one of the most intelligently made portable devices I’ve used in years. I highly recommend it. Other Questyle dongles will be reviewed asap.
