Fiio M15S DIGITAL AUDIO PLAYER REVIEW

Fiio are a name synonymous with personal audio and in this review, Oscar Stewart takes a listen to their M15s DAP.

Fiio does not really need much of an introduction, they are a big name in the portable and personal audio world and have been making audio products for a few years now. Founded in 2007 they quickly became known for making excellent digital audio players (DAPs) but they also have a range of desktop DAC/Amps, headphones, earphones, and accessories. 

My experiences with Fiio date back many years and, for me, have always managed to make products that give you excellent playback quality for a reasonable price. The M15s is one of their latest DAPs and comes in at £979, this model is designed for playback on the go and comes with a stand for use as a DAC/Amp at home too. This isn’t their flagship model, but it does aim to provide the best combination of both portability whilst maintaining a suitable desktop power output. 

FEATURES AND BUILD QUALITY

It’s hard to know where to start with such a versatile device, but let’s start with the operating system. The M15s runs on Android 10 and whilst this isn’t the most up-to-date OS it still supports all the current streaming apps. The Android operating system gives you some flexibility to allow you to install apps should you wish to use this for streaming duties around the home, or download playlists for offline playback. It also means the settings menu has all the features you could want in an easy-to-navigate system.

The M15s has 6 operating modes: Android, Pure Music, AirPlay, USB DAC mode, Bluetooth Receiver, and Roon Ready – these all do pretty much what they say. Pure Music mode is best for playing back local files without unwanted background processes, Android mode gives you an Android-focused UI, Airplay allows you to stream from your Apple device to the M15s for better quality playback, USB DAC allows you to use the M15s as an external DAC/Amp, Bluetooth receiver mode supports Bluetooth 5.0 SBC/AAC/Aptx/Aptx HD/Aptx LL/Aptx Adaptive and LDAC allowing the M15s to act as a high-quality Bluetooth receiver and Roon ready sets the M15s as a Roon endpoint allowing you to stream to it via Roon in your home system. 

On the bottom you have a tray for a micro-SD card; the onboard storage is only around 46gb once the OS is taken into account, so a micro-SD is the best way to store local music files. You also have the USB-C charging port on the bottom which is also used when in USB DAC mode. When charging via a QC/PD fast charger the M15s can increase its power output by 21% due to using a higher voltage power supply internally – excellent for powering harder-to-drive headphones. In desktop mode, you can turn off charging, which is handy for protecting the battery. On one side you have playback buttons (FF, RW, Play/Pause and Power), on the other, you have a hold button, volume up/down and a multi-function button that allows you to change the operating mode. On the top you have a volume wheel (you can choose between the wheel or buttons for volume control) along with the outputs (3.5mm single-ended, 2.5mm and 4.4mm balanced).

The screen is easy to read and responsive, there are 5 gain levels which should suit most headphones and the balanced output can hit 1200mw per channel max output at 32Ohms. Internally the M15s uses a Qualcomm 660+ processor, QCC5124 Bluetooth chip and ESS9038 Pro DAC chip. There is a multi-stage power supply that allows for clean power that’s able to support both low and high-impedance loads and the audio data passes through FPGA with custom femtosecond crystal oscillators to provide a high-precision/low jitter unifier clock source for the entire audio architecture. 

The build quality is excellent! The main case is made from machined aluminium and internally there is shielding for the critical audio components. Fiio use Graphene technology for heat dissipation and the rear panel is made of glass, just like the front. It comes with a brown leather case for protection and there is a lovely metal backplate that is vented to keep the device well ventilated. Fiio has really thought about the design and features of the M15s to make it an excellent on-the-go portable player that also doubles up as a desktop DAC/Amp when needed.

USABILITY

I mostly use a DAP for out-and-about listening duties, preferring to listen to local FLAC files ripped from CD over streaming from a phone and using a dongle. The M15s was a joy to use in this aspect, using the Pure Music mode you get all the usual playback features along with various digital DAC filters and gain settings. Browsing was easy and the physical buttons are well placed, the hold switch is a great addition meaning you won’t accidentally change the volume or skip tracks in your pocket.

I found myself preferring to use the volume knob for adjustment as it just felt much nicer to use than the buttons. The knob is linked to an encoder so you still get very fine volume control and the gain levels help in this respect too. There’s a light ring around the volume knob which you can decide how the colours change (based on codec, volume or others), you can set a max volume limit, and there’s balance control (great if you have imbalanced hearing) and you can set the outputs as fixed Line-Out or the normal variable headphone output – handy for integrating into a HiFi setup should you wish.

Battery life is around 9-10hrs – this should be plenty and it does support fast charging should you require a quick recharge on long journeys. Luckily being a DAP, it can charge and play at the same time, so it’s unlikely the battery life will ever be an issue. 

So, we’ve established that the M15s is quite a feature-packed DAP, but it can’t just be good to use, at the end of the day we want to know if it sounds good too.

SOUND

I’ve been putting the M15s through its paces by using it as a daily player for my commute with my 64 Audio A6t custom in-ears and also using it at home with some full-size headphones, and I must say I am really impressed with its handling of music playback. 

The M15s has a way of sounding very convincing; it is not trying to show off by throwing technicalities at you, but it isn’t holding back and doesn’t sound veiled either. It sounds neutral, but not unnatural. It is effortless and has excellent resolution, but without sounding dry or analytical. The bass is rich yet well controlled, the midrange is clean and the treble is sweet yet well extended – it’s a sound that is enjoyable to listen to without sounding coloured as such. 

The M15s made me smile the other day; I was walking to work when Linkin Park/Jay-Z – Dirt off Your Shoulder / Lying from You came on through my 64 Audio A6t. The music was presented in such a fun way with excellent extension and air, instead of trying to pick apart the song I just got lost in the music. My old iBasso DX200 has always been my reference player, and it does sound a little more analytical, but also a little flat when it comes to dynamics.

I plugged the Sennheiser HD660 S2 into the M15s via the 4.4mm output expecting to have to turn it up a little, yet with the volume at 50 and on low-gain I was getting good listening levels from them. It wasn’t just driving them; it was pumping out really excellent quality of sound from such a small player. The bass was deep and articulate, the midrange nuanced and the treble was airy. Listening to Deolinda – Bons Dias the acoustic guitars have excellent tonality, the double bass reaches low and the female vocals are rendered beautifully. 

I decided to see how the M15s would handle my German Maestro GMP400 headphones. These are a 300Ohm pair of full-size studio headphones – and whilst I prefer the signature with a good valve amp the M15s provided more than enough output to get them to listening levels with ease. I was really impressed with how the M15s handled these headphones, with great separation, control, and detail. Whilst these are not a full-bodied headphone, the M15s was outputting enough power for them to sound as good as when used with a few solid-state desktop amps.

Green Day – Jesus of Suburbia through the M15s and paired with my trusty Grado SR80 was such a blast; every kick is well separated, Billy Joe’s vocals well defined, and the crunching guitars had plenty of power. There is a sense of poise and control to the sound, yet the M15s still knows how to have a good time. This setup easily gets you tapping along, it is dynamically engaging yet perfectly balanced sound-wise, it’s easily a reference tuning, but one that is not boring. 

QUIBBLES

I don’t have too many quibbles with the M15s at all. No, it’s not the smallest DAP out there for daily use but then again you wouldn’t get this level of power or features from a smaller size. I guess the fact it is running on Android 10 is a little bit of a letdown, they really should update it to a newer Android version in the future.

CONCLUSION

The Fiio M15s treads the line between being an utterly ruthless reference-sounding DAP, and one that is enjoyable for daily listening. The sound is perfectly balanced with great power and dynamics, yet it never sounds like it is trying to colour what you are listening to. It’s clean and punchy, it will let you hear all the detail you could want without sounding clinical and it works well with a huge range of headphones. 

It’s an incredibly versatile player that allows you to listen to locally stored music along with being able to stream, airplay and Bluetooth to it, or use it as a Roon endpoint. The included stand and the fact you can increase the output by using a QC/PD fast charger are great little added features. This will happily double up as a desktop source and work well in this role for a lot of headphone users. 

Honestly, the M15s is just a joy to both use and listen to, and I don’t think many would be let down by its performance, especially when you take into account the price. 

AT A GLANCE

Build Quality And Features:

Solid build quality

Tons of features (Android, Bluetooth, Airplay, Roon, USB DAC)

Multiple outputs (3.5mm, 2.5mm, 4.4mm)

Excellent screen

Sound Quality:

Punchy and dynamic

Clean and detailed

Reference level tuning without sounding overly analytical

Value For Money:

There are a lot of DAPs out there but the M15s does, however, represent great value considering it works well as a desktop source as well as a portable one. You might get a hint of extra detail and resolution from a costlier device but, this is the sweet spot where most people really wouldn’t ask for more from a sound quality perspective. 

We Loved:

Brilliant sound in terms of quality and output power

Easy to use 

Versatility

We Didn’t Love So Much:

Running on an older version of Android

A little bulky for some

Elevator Pitch Review: The Fiio M15s is pretty much all the DAP most headphone users need; it has got loads of power and sounds like a reference device without coming across as boring. It’s feature-packed and doubles up as a desktop source – what’s not to love?

Price: £979 / $999.99 / €999

Oscar Stewart

SUPPLIED BY Fiio

SUPPLIED SPECIFICATIONS

• High-End ES9038Pro DAC Chipset
• Snapdragon’s Latest 660SoC Chipset
• Big 5.5” Display Screen and Latest Android 10 OS
• 4GB RAM For Smooth Multi-Tasking
• 64GB Internal Storage and supports micro SD card up to 2TB
• Qualcomm’s Latest QCC5124 Bluetooth Chipset
• Two-Way High-Res Bluetooth Connectivity
• Two-Way USB 3.0 Connectivity
• Integrated RGB Indicator in Volume Wheel
• Balanced Line-Out Support
• High-Power Output (Up to 1.2W per channel)
• Apple Music, Roon Ready
• Dual Power Supply Mode supporting
• Desktop Mode Support
• Disable Battery Charging While Using USB DAC Support
• Including FiiO DK3S Cooling Stand