FiiO M15S DAP Review – A Beast That You Can Actually Take With You

FiiO says, “Bring It On” to the many competitive DAPs and power-hungry headphones out there.

Unboxing and First Impression

Company Overview

Since its launch in 2007, FiiO has done a remarkable job building its hard-earned reputation through innovative in-house R&D, quality products, and extensive industry accolades – not celebrity endorsements and marketing hype. FiiO has a raving, loyal fan base worldwide because they have consistently delivered excellent products with exceptional innovation, performance, quality, and value.

Packaging

This is a rare occasion where the product has to live up to the imposing presence of its box. A fancy outer sleeve covers a premium, heavy-duty silver box. Dense foam blocks precisely cradle the M15S, stand components, and accessories inside. I appreciate FiiO’s balance of high-end packaging with thoughtful, space-efficient packaging design.

In the box

• FiiO M15s
• Leather protection case (pre-installed)
• Powered multifunction dock with heat dissipation fan
• PD charging/data cable (USB-C to USB-C)
• USB-A to USB-C power cable
• USB-C to USB-A adapter
• Pamphlet, quick start guide, stand assembly card, warranty card, and tip card
• Micro SD card removal tool

Build & Design

Stunning. It may be even more impressive to hold than to look at. Though the M15S feels physically big and substantial, it isn’t as large or heavy as it first appears. The case and thin bezel 5.5”1 8:9 HD display screen accentuate this impression.

It feels heavy due to its densely packed internals. Nothing rattles or shifts inside or out, even with aggressive movement. It is one-hand operable if you have XL-sized hands.

All parts feel tight and precise. Fit and finish are flawless – even the gaps around the buttons are minuscule and consistent. Said buttons are easy to locate sight unseen, even when the M15S is safe in its case.

The buttons on both sides of the DAP are my only gripe. They are tactile, require little force to press (even with the case), and are positioned exactly where my hands go when picking up the device. Unless I slide enable the hold switch or disable the functionality of the buttons, I constantly press the buttons unintentionally.

The rear panel appears to be glass, with diamond-cut-like angles visible, just below a shiny, perfectly flat outer surface.

120 volume levels can be finely adjusted using an analog potentiometer knob (rotating wheel) or the side buttons. The wheel rotates smoothly with adequate resistance to avoid inadvertently rolling it too far and fast, damaging your gear and ears in a painful 2-for-1 accident. The high-precision rotary encoder ensures minimal wear and reliability with every turn of the knob.

Internals

Current DAP manufacturers continue to one-up each other on leading technology and specifications. The M15S is no exception.

The technical highlights are seemingly endless. They sound mighty impressive, even though only engineers will likely understand any of it. Among these is a high-performance ES9038PRO DAC with eight independent D/A converters. Each channel uses four D/A converters in parallel to form a fully differential output.

There is also a comprehensive multi-stage audio circuit. High-precision, low-noise film resistors enable accurate signal reproduction and channel balance. Panasonic low-loss metalized film capacitors ensure minimal harmonic and phase distortion.

The M15S has a fully separated digital power supply, reducing crosstalk and interference efficiently. The multi-stage analog power supply provides high-precision and low-noise early signal processing. A multi-voltage servo power supply for the headphone amp can drive both low and high-impedance loads.

A nickel-copper shield is present to protect the analog portion of the audio circuit and the main SoC (system-on-a-(micro)chip) from interference. Additional heat dissipation is achieved with shielding materials and wave-absorbing paper stacked onto the main shield.

Advanced heat dissipation design, featuring a stainless steel battery compartment, low temperature-drift components, and a dedicated metal shield with graphene, ensures that the M15S maintains a stable temperature and continuously delivers high power output.

Beyond the engineering and technical prowess, the M15S boasts the best of today’s technology and specifications. From a user perspective, this means flawless execution as designed. Everything works perfectly and consistently.

Usability

Usability and stability are excellent. Startup is fast, connectivity is stable, power management is excellent, navigation is smooth and quick, and the controls work as intended. Double tap to wake up the screen is a bonus! The M15s offers wireless features such as AirPlay, DLNA streaming and transmission, and Bluetooth. The Qualcomm QCC5124 chip ensures reliable 2-way Bluetooth performance.

The 6200mAh battery provides up to 10.5 hours of operation using single-ended or balanced output. Battery optimization and protection systems ensure longevity, with a charging time of just 3.5 hours.

The tradeoff of a powerful battery and amplifier is heat, making the somewhat thick M15S even less pants-pocket friendly.

The M15S is so good at dissipating heat that the screen can reach temperatures of almost 100 degrees Fahrenheit under normal loads.

The Android 10 operating system has been flawless. FiiO’s software is pre-loaded and useful. The best part? You can download and access the Google Play Store and install and use any apps you want, just as you would with an Android phone.

The M15s offers six operating modes:

1. Certified Roon Ready Mode
2. FiiO’s exclusive Pure Music Mode
3. Android Mode: Freely use third-party apps, including streaming services
4. AirPlay Mode: Wirelessly connect to iOS devices like iPhone/iPad with a sound quality boost
5. USB DAC Mode: Acts as a DAC when connected to a computer/phone for improved sound
6. Bluetooth Mode: Supports various codecs like SBC, AAC, aptX, aptX HD, aptX LL, LDAC, and aptX Adaptive for high-quality wireless sound

FiiO M15S Sound

With low output impedance and high power, the M15S is a good match for most IEMs or headphones. With five adjustable gain levels, a dedicated desktop mode provides up to 1200mW per channel while plugged into a power source, bypassing the battery.

Combined with the cooling stand, the M15S can truly be a desktop replacement.

The M15S, on any gain setting, has a beautifully deep black background – zero noise. In addition, I have not noticed any discernible distortion at any volume with any output device.

In addition to low distortion and almost perfect performance measurements, the sound profile, to my ears, is accurate, transparent, clean, and uncolored. The M15S reproduces dynamics well with super easy and difficult-to-drive headphones. I have only compliments for the M15S’s sound.

For audio tinkerers, the software-based 10-band dynamic EQ with adjustment parameters of ± 12dB will allow for precise sound sculpting. Even better, the M15S supports saving custom EQ profiles.

Where to Buy

• FiiO
• Amazon

Conclusion

DAPs are difficult to produce to everyone’s needs. There are always tradeoffs in size, weight, power, and capability, to name a few. In my opinion, FiiO’s M15S successfully addresses those compromises to the highest degree possible, finding an optimal balance to appeal to audiophiles who want a legitimate all-in-one alternative to a much larger or multi-device desktop setup.

FiiO designed and built the M15S for audiophiles and enthusiasts.

This is a niche product for listeners who want the best available and who really understand their specifications and requirements.

Even when the internals are outdated, the M15S will remain a top performer for its useful life. It’s hard to imagine another device significantly outperforming the technical and audio capabilities of the M15S. The user interface preferences will matter more, and those will evolve over time.

Is it expensive? Yes, for a general consumer who uses mostly Bluetooth devices and mobile phones as their source. For enthusiasts who want a premium product with few compromises, it’s a great investment to declutter and uncomplicate your music life.

The FiiO M15S goes with me everywhere!

Technical Specifications

• Form: Portable Digital Audio Player (DAP)
• Frequency Response Range: 20Hz – 20kHz, up to 20Hz – 50kHz
• Color: Black/Silver
• Display: 5.5” 18:9 HD display
• Operating System: Android 10
• CPU: Qualcomm Snapdragon 660
• Memory: Ram 4GB, ROM 64GB + single MicroSD card tray (up to 2TB)
• Hi-Res Support: 32-bit/768kHz, DSD512, MQA Global 8x decoding, and All to DSD
• Bluetooth: Qualcomm QCC5124 with two-way Bluetooth 5.0
  • Bluetooth transmitter Codec support: SBC, AAC, aptX, aptX HD, LDAC, LHDC
  • Bluetooth receiver support: SBC, AAC, aptX, aptX HD, aptX LL, LDAC, aptX Adaptive
• WiFi: 5G + 2.4G dual-band WiFi, supporting DLNA streaming and transmission, Roon, and AirPlay
• DAC: ESS ES9038PRO
• Amplifier: OPA926 *2
• Crystal Oscillator: NDK femtosecond crystal oscillator x 2
• Output Power: Up to 1200mW x2 @32Ω (balanced continuous output)
• Gain: Ultra high, super high, high, medium, low
• Headphone Output: 3.5mm single-ended, 2.5mm + 4.4mm balanced
• Recommended Headphone Impedance: 8-150Ω (single-ended output), 8-350Ω (balanced output)
• Line Output: 3.5mm, 2.5mm balanced + 4.4mm balanced
• Coaxial: 3.5mm
• Output Impedance: ≤2.3Ω
• THD+N: ≤0.00075%
• SNR: ≥121.5dB
• Noise Floor: ≤5.2uV
• Peak Output Voltage: 30Vpp
• Degree of Separation: ≥105dB
• Power Supply: Supports QC3.0, 4.0, PD2.0, 3.0 quick charge
• Battery: 6200 mAh
• Charging Time: 3.5 hours
• Battery Life: Up to 10 hours in single-ended and 8.5 hours in balanced; standby time >1000h
• Working Modes: Android, Pure Music, USB DAC, Bluetooth Receiving, AirPlay, Roon Ready
• Dimensions: 140 x 80 x 18.9mm
• Weight: 346g