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Golden Ears: Fiio M15S Digital Audio Player Review

Christopher Coke Updated: Posted:
Hardware Reviews 0

In the world of smartphones, you might think dedicated digital audio players (DAPs) were a thing of the past. But while the iPod might be a thing of the past, DAPs have been quietly becoming a favorite accessory of dedicated audio enthusiasts. Today, we’re looking at one of the most impressive players that’s come across our desk, the Fiio M15S. Featuring an incredible 1200 watts of power, Android 10, multiple output options, and the ability to connect to a PC to transform into a fully self-enclosed audio system, it’s the kind of all-in-one solution that can elevate your listening anywhere you go. 

At $999, it’s the perfect Golden Ears product. In this semi-regular column, we take a close look at the world of high-end audio. The prices and product scale up to incredible levels and make big promises — but what do you actually get for that higher cost of entry? That’s exactly what we’re here to find out. 


Current Price: $999 (Amazon

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Fiio M15S - What Is It?

The Fiio M15S is a desktop-class digital audio player designed to be a complete listening solution whether you’re on the go or enjoying music at your desk. On its own, it’s a portable smart device complete with Android 10, the Google Play Store, and a powerful enough processor and memory combination to run the latest music apps without lag. Plugged into a PC over USB Type-C, it becomes an external soundcard, a portable DAC/amp hybrid that can elevate your entire listening experience. 

While the M15S has a lot going for it, which I’ll break down throughout this article, one of its most defining features is its tremendous power output. Over its balanced connection, it delivers up to 1200 watts of power output, which is sufficient to drive just about any headphone you could buy today. Through its single-ended connection, it can output 580mW. Clearly, it’s intended to be listened to through its 4.4mm balanced connection, but there’s plenty of headroom for most headphones and IEMs even through its standard 3.5mm jack. Note that these wattages are slightly less when running off battery, so you’ll need to plug in to unlock its highest power output, but this is understandable given how much juice is required for that mode. 

When we reviewed the Fiio M11 Plus ESS last year, we were impressed by its build quality, feel, and usability and that’s even more so here. The M15S is large, which is understandable given its higher power output. I wouldn’t call it pocketable, but it is portable and can easily be thrown in a bag or suitcase when traveling. It’s thicker than the M11 Plus, bigger in every dimension by several millimeters in fact, but feels perfectly sized and balanced for single-handed use. 

The button layout is also improved. On the right side of the unit, you have volume up and down down controls, a hold switch to lock buttons from accidental presses, and a programmable button you can set for different functions, like favoriting songs. On the left are track controls (back, next, play/pause) and the power button. There’s also a volume knob on the top which is guarded by a leather flap when used with the included case. Instead of being on the right like the M11 Plus, the microSD card is positioned on the bottom next to the USB Type-C port for easier access. Along the top are three output jacks, 3.5mm single-ended and 2.5mm and 4.4mm balanced outs. 

Functionally, it’s just plain easier to use. Not that the M11 Plus ESS wasn’t, but you can tell that there has been some extra consideration made, and it really shows throughout its design. 

The actual construction is also improved. The player uses a metal body on the top and sides with a 5.5 inch IPS screen on the front and a glass back cut with an intricate angular pattern that flashes and shines as it catches the light. This design helps to shed the inevitable heat that comes from its powerful amplification circuit but also makes it feel especially robust. The glass back might be concerning if it weren’t for the stellar leather case that Fiio also includes to keep it safe from damage.

Inside that durable shell are top-shelf audio components that put sound quality at the top of their priority list. It uses an ESS ES9038PRO Sabre DAC chip capable of 32-bit/768kHz audio, MQA 8x decoding, and DSD 512. For amplification, it uses two OPA926 amplifiers fed by a separated power supply depending if you’re listening with USB power or on battery, eliminating cross-talk and distortion from blended power. The entire audio system is kept in perfect phase with Fiio’s FPGA system and a pair of Japanese femtosecond oscillators. Audio is driven across eight channels and is guarded with multiple layers of shielding to prevent interference and help dissipate heat. 

The system uses Android 10 for its operating system and a Snapdragon 660 with 4GB of RAM. These aren’t cutting edge specs compared to modern smartphones but are perfectly sufficient to run streaming apps, music players, EQs, and even browse the web and social media. There’s a bit of stutter when scrolling long Spotify lists but it’s not bad, especially compared to other players on the market today. Still, I would have preferred to see it ship with a newer OS version and SoC.

As a wireless device, it also supports connecting over Bluetooth. It can transmit audio with SBC, AAC, aptX, aptX HD, aptX Low Latency, LDAC, and LHDC. It can receive audio in all of these formats, as well as aptX Adaptive.

When used as a wireless device, it has surprisingly good battery life. It features a 6200mAh battery, which is frankly huge, but it needs to be. With such high power output, it uses a lot of energy. Over its balanced output, it promises nine hours of listening and around ten over single-ended. This varies depending on your volume but there’s enough headroom where you really won’t need to crank it to very high levels, so I found the battery life to be about accurate. 

The M15S has another trick up its sleeve: plugged into a PC over USB Type-C (or with a compatible PD charger), it can enter Desktop Mode. This mode is able to bypass the battery entirely and unlocks the full  wattage the player can provide. Windows immediately recognizes the M15S as an audio device and hands off full control of your system audio by setting it to default. It’s an instant transformation, upgrading your PC to top-tier listening no matter how high quality its built in audio may be. 

Used in this mode with is higher power output, heat can be a concern but Fiio has a solution. Also included in the box is a desktop stand with a built-in fan. It also raises the player up so it’s easy to access to control your system audio. 

Built-in storage is only 64GB, which is closer to 46GB for usable space. This can be expanded up to 2TB using a microSD card, which most users purchasing a device like this will want to do. 

Which brings us to its six different operating modes. If you’re listening to local lossless audio files and don’t want to spend battery on Android processes, you can go to Pure Music mode. There’s also Roon Ready mode for easier integration with Roon, AirPlay mode, USB DAC mode, Bluetooth receiver mode, and standard Android Mode. These options allow you to balance performance with how you’ll actually be using it. It’s wonderfully versatile, which is exactly what you want from a device in this class. You can easily use it to elevate your listening experience just about everywhere and its operating modes encourage exactly that.

Fiio M15S - Performance and Listening Impressions

Let’s get this out of the way first: The M15S sounds fantastic. It’s a noticeable sonic upgrade over the M11 Plus ESS. The sound is warm, full, and dynamic. The background is black, enhancing the audible dynamic range. This is a DAP that can push your headphones to their fullest without overly coloring the sound in the process.

I tested the M15S with a mix of IEMs and headphones, including the Raptgo x HBB: Hook, the Meze 109 Pro, the Dan Clark Aeon Open X, the Hifiman Ananda and Arya, the Kiwi Ears Orchestra, and the AFUL Performer 5. It was a healthy mix of demanding and sensitive gear and the M15S handled all of it with aplomb. Using the five built-in gain modes, it was able to drive everything I threw at it without undue noise, hiss, or distortion.

The sonic character is on the neutral side. It’s not as cold as THX amps tend to be but also isn’t overly warm like other ESS Sabre DACs we’ve tested. This is a player that’s about pushing your headphones to their potential not shading the listening experience with its own character. 

Practically speaking, that’s a very good thing. IEMs and headphones are, after all, the most impactful element of your whole listening experience. Allowing your listening device to perform at its peak means you’ll hear everything it has to offer, at its full potential. The Hook, for example, had deeper, more impactful bass on the M15S than on my usual dongle DAC or even on the Fiio BTR7. 

The M15S offers excellent dynamics. Layering and detail retrieval are excellent. There’s no masking at all here. It’s well-tuned to drive, so if you’re used to listening straight to desktop audio, you’ll likely be surprised at just how much it lets you hear compared to what you’re used to. 

The software experience is fine, standard Android fare. Fiio has built a number of custom options into the software. It takes some effort to dig in and see what it has to offer, and I wish some of it was explained better. For example, while the marketing boasts multiple preset EQs, there’s no system-level way to apply these (they’re built into the Fiio app; you can install something like PowerAmp EQ to apply your own curve to the whole system). There are also neat features like All to DSD mode, though what this actually does isn’t explained anywhere (though it’s a bit in the name, it just converts everything to DSD).

There are also other options, like the ability to remap the multifunction or adjust maximum volume. You can also apply some fine-tuned adjustments like Second Harmonic Regulation, which impacts the treble slightly. All of these are hidden in the settings menu, so it’s worth taking time to explore.

At its core, though, it’s a pretty simple device and it works well. Once you have the settings dialed in, the biggest thing you’ll adjust is the gain level which is a simple toggle in the pull-down menu. The software and hardware are performant enough that you can browse the web as you listen to music and not suffer any major slowdowns. The biggest issue minor stutters as you scroll long webpages, but it’s hard to be too upset when it’s a music device first and foremost and performs perfectly there.

Final Thoughts

At $999, it’s only right to expect big things from the Fiio M15S and it delivers. Yet, at the same time, it’s clear that this isn’t a device for everyone. It’s a player for dedicated audiophiles who want top-tier listening everywhere they go. If that describes you, you can rest assured that this is a fantastic choice. I wish it a slightly newer chip, OS, and a couple of gigabytes more memory, but it achieves what it sets out to do very well. If this sounds crazy to you, well, you’re not the target audience. If you’re hearing it and thinking that it sounds like a good solution for excellent audio everywhere you go, it’s absolutely worth considering.

The product described in this article was provided by the manufacturer for evaluation purposes. Some articles may contain affiliate links and purchases made through this will result in a small commission for the site. Commissions are not directed to the author or related to compensation in any way.

  • Outstanding sound quality
  • Excellent performance
  • Google Play Store = easy access to apps
  • Tremendous power output
  • Wide compatibility
  • Extremely expensive
  • Older OS and SoC


Christopher Coke

Chris cut his teeth on MMOs in the late 90s with text-based MUDs. He’s written about video games for many different sites but has made MMORPG his home since 2013. Today, he acts as Hardware and Technology Editor, lead tech reviewer, and continues to love and write about games every chance he gets. Follow him on Twitter: @GameByNight