The Fiio M15S delivers superb sound quality, priced $999, featuring a well-engineered audio circuit that ensures a clean, dynamic, and balanced audio performance. The device leverages advanced technology such as a 4th-generation FPGA and dual Japanese crystal oscillators. These components help minimize jitter and ensure a high-resolution audio experience with reduced noise interference. This makes the M15S capable of delivering precise and accurate sound reproduction.

In terms of tonality, the M15S excels with clean highs, detailed mids, and robust lows. The highs are particularly clear, free from any hiss even at lower volumes, which enhances listening across various music genres. The mids are dynamic and provide excellent vocal clarity, making the M15S ideal for tracks where vocal performance is prominent. The player also shines in the lows, delivering deeper and more consistent bass without distortion, even at higher volumes.

Specifications Overview:

• System on Chip (SoC): Snapdragon 660
• DAC: ES9038PRO
• Amplifier: Dual OPA926
• Oscillators: Two NDK femtosecond crystal oscillators
• Operating Modes: Includes Android mode, Pure music mode, USB DAC mode, Bluetooth receiving mode, AirPlay mode, and Roon Ready
• Weight: 346 grams
• Volume Control: Both button and knob types
• Dimensions: Approximately 140 x 80 x 18.9 mm
• Internal Storage: 64GB, expandable up to 2TB via microSD
• Screen: 5.5-inch full-fit display
• Gain Settings: Ultra high, super high, high, medium, low
• RAM: 4GB
• Headphone Outputs: 3.5mm single-ended, 2.5mm and 4.4mm balanced
• Line Outputs: 3.5mm, 2.5mm balanced, and 4.4mm balanced
• Digital Output: 3.5mm coaxial
• Connectivity: Dual-band WiFi (2.4GHz/5GHz) and Bluetooth 5.0 with extensive codec support including SBC, AAC, aptX, and LDAC
• MQA Support: Global 8x decoding
• USB Audio Support: Up to 32-bit/768kHz and DSD512
• Equalizer: 10-band dynamic EQ with eight presets and custom settings
• Power Features: Compatible with QC3.0, 4.0, PD2.0, 3.0 quick charging
• Battery: 6200mAh with a charging time of 3.5 hours
• Standby Time: Over 1000 hours
• Headphone Output Specifications:
• Power Output: 531mW x 2 @16Ω
• Output Impedance: ≤2.3Ω
• THD+N: ≤0.00075%
• SNR: ≥121.5dB
• Noise Floor: ≤5.2uV
• Peak Output Voltage: 30Vpp
• Separation: ≥105dB
• Frequency Response: 20Hz-20kHz

The Fiio M15S also offers versatile gain settings to accommodate a wide range of headphones, from sensitive in-ear monitors to more robust, high-impedance models. This flexibility ensures that the M15S can effectively drive different types of audio equipment with ease, providing an adaptable solution for various audio setups.

Overall, the Fiio M15S is a standout choice in the digital audio player market, offering high-fidelity sound that competes well with other high-end portable music players, making it a solid investment for audiophiles…

…The review isn’t over. I wanted to emphasis on some details I found worthy.

Fiio M15S DAC Section__

Diving deeper into the technical prowess of the Fiio M15S’s DAC, it is evident that meticulous attention has been given to ensuring superior audio quality and precision. The device employs a top-tier DAC chip, typically found in high-end audio equipment, which contributes to its ability to deliver exceptionally clean and articulate sound. This chip is designed to minimize noise and distortion, which is crucial for maintaining the purity of the audio signal. The dual DAC setup not only allows for balanced audio output but also enhances the stereo separation and width, creating a more immersive listening experience.

The DAC’s performance is further boosted by the use of advanced clocking mechanisms that control timing errors or jitter, which are often detrimental to audio fidelity. The integration of femtosecond crystal oscillators is a standout feature, offering an ultra-low phase noise that ensures the audio signal is rendered with high precision and detail. These oscillators work in tandem with the DAC to stabilize the digital signal before it is converted, thus preserving the integrity of the original recording.

Furthermore, the M15S’s DAC supports a wide dynamic range and has a flexible filter section, allowing users or at least me to tailor the sound profile to their / my preferences. The filters adjust the phase and frequency response of the DAC, enabling subtle shaping of the audio output, whether the user prefers a warmer tone or a more analytical sound. This level of customization is indicative of Fiio’s commitment to catering to the nuanced needs of audiophiles, offering them a device that not only plays music but also enhances their overall listening experience. This combination of cutting-edge DAC technology, precision clocking, and user-customizable options sets the M15S apart in a crowded market of portable audio players.

Desktop Mode__

The Fiio M15S features a unique “Desktop Mode” designed to enhance its functionality when used as a stationary device, rather than just as a portable audio player. The only way to enable this feature is after plugging a high speed charging cable. This mode is particularly useful when you want to connect the M15S to external power, allowing the device to bypass its battery and operate directly from the power supply. This has several advantages, including the ability to drive higher voltage requirements without depleting the battery and potentially delivering even better sound quality by reducing any power-related constraints.

In Desktop Mode, the M15S increases the voltage rails, which provides more headroom for the DAC part and increases the output power for the headphone amplifier. This means the M15S can deliver a more dynamic and open sound, enhancing the listening experience, especially when using high-impedance headphones that require more power.

This feature underscores the M15S’s versatility, making it an excellent choice for users who desire a high-quality sound system that can perform exceptionally well both at home and on the go.

Android and Pure Music Modes__

The Fiio M15S offers two specialized modes designed to optimize the user experience based on their specific listening and functional preferences: Android Mode and Pure Music Mode.

Android Mode on the M15S is essentially what you’d expect from a typical Android device. It allows the user to access and use third-party apps, including popular streaming services, through the Google Play Store. This mode is particularly useful for those who appreciate the flexibility of a standard Android environment, combining both high-quality audio playback with the functionalities of a smart device. It supports all the regular Android features such as Wi-Fi connectivity, app installation, and web browsing, making the M15S a versatile tool not just for listening to music but also for a variety of multimedia experiences.

Pure Music Mode, on the other hand, is tailored for audiophiles seeking a dedicated music listening experience. This mode strips down the operating system to just the essential audio functions, shutting down all non-essential processes and background applications that might interfere with audio playback. By focusing solely on music playback, Pure Music Mode minimizes any potential digital noise and optimizes the device’s resources for the best possible sound quality. This mode is ideal for critical listening sessions where the purity of the audio is paramount.

The key difference between these modes lies in their intended use and performance impact. Android Mode offers flexibility and a broad feature set for general and multimedia use, whereas Pure Music Mode focuses on delivering the highest quality audio experience by eliminating potential sources of interference and optimizing the device’s audio processing capabilities. These options give users the freedom to choose how they want to experience their music, whether they prioritize versatility or sound quality.

Gain and TORQUE___

The Fiio M15S features several gain modes designed to accommodate different types of headphones / iems / speakers and listening preferences. These modes allow the user to adjust the output power of the device to match the sensitivity and impedance of the earphone being used, optimizing both the sound quality and volume levels.

The M15S offers five different levels of gain: low, mid, high, very high and ultra-high. Low gain is ideal for highly sensitive in-ear monitors (IEMs) that require minimal power to achieve optimal sound quality and volume. Using a lower gain setting prevents the potential for hissing or overly loud output that could damage both the headphones and the listener’s ears. Mid gain is suitable for regular headphones that have a moderate impedance and sensitivity, providing a nice balance of power without overdriving the audio.

High gain, on the other hand, is designed for earphones that have a higher impedance, requiring more power to reach adequate volume levels. This setting ensures that even less sensitive headphones can produce a full and dynamic sound. Very high and super high is too, actually it’s name speaks for itself. Lastly, Ultra High gain is only activated when the device is used in Desktop Mode, connected to external power. This mode provides additional voltage and power, ideal for driving power-hungry, high-impedance headphones during stationary listening sessions, enhancing the dynamic range and overall sound clarity.

The choice of gain mode significantly affects the M15S’s performance with different headphones. Lower gains are perfect for preserving the clarity and detail in sensitive headphones, while higher gains are essential for unlocking the full potential of more robust headphones. This adaptability allows users to customize their listening experience according to their specific audio equipment and preferences, ensuring that they always get the best possible sound from their device.

• Increasing gain in audio equipment is similar to increasing torque in a vehicle. In sound systems, particularly amplifiers, increasing the gain raises the power level of the audio signal, allowing for greater sound output. This is akin to enhancing the torque in a vehicle’s engine, which increases the rotational force the engine can generate, thus enhancing the vehicle’s acceleration capability.
• Both scenarios aim to maximize the system’s output capacity like faster acceleration in vehicles and higher sound levels in audio systems. However, in audio systems, setting the gain too high can sometimes lead to unwanted noise, such as background hiss, similar to how excessive torque can cause handling issues in vehicles. Therefore, proper adjustments in both scenarios are critical for maximizing efficiency and functionality.

Pros:

– High-quality DAC and powerful amplifier

– Advanced heat dissipation technology

– Supports multiple high-resolution audio formats

– Versatile with Android Mode and Pure Music Mode

– High-quality, larger touchscreen for improved usability

– Sleek design with robust build quality

– Portable despite its high performance

Cons:

– Reduced battery life compared to the predecessor

– Larger and heavier than previous models, affecting portability

– Higher price point, making it less accessible

– Limited Android version support over time

– Screen resolution remains the same despite larger size

Fiio M15S Review Conclusions

The Fiio M15S stands out as an exceptional digital audio player, combining high-end audio capabilities with versatile functionality. Its sound quality is impeccable, supported by advanced DAC technology that ensures clean, dynamic, and balanced audio across all frequencies. The device caters to both casual listeners and audiophiles through its Android and Pure Music Modes, allowing for either a feature-rich multimedia experience or a focused, high-quality listening session. Additionally, its gain settings are adaptable to a wide range of headphones, enhancing its utility for various audio setups. Whether used in a stationary setting with its Desktop Mode or on the go, the M15S proves to be a robust player that meets the nuanced demands of today’s audio enthusiasts.

Further enhancing its appeal, the M15S’s design and build quality speak to Fiio’s commitment to both functionality and aesthetic appeal. The larger screen and intuitive interface offer an enjoyable user experience, while the solid construction ensures durability. Although the reduction in battery life compared to its predecessor might be a concern for some users, the overall performance and sound quality of the M15S more than compensate for this shortcoming. Ultimately, the Fiio M15S offers excellent value, combining high-performance features with a sleek design, making it a highly recommendable choice for anyone looking to invest in a top-tier portable audio player without top tier price.