FiiO S15 review

We know FiiO best for its feature-laden portable music players and affordable digital-to-analogue converters, but, as we take a look at the company’s website, the sheer breadth of its product range is astonishing. You’ll find countless headphones of all types alongside active speakers, desktop audio products, cables and even a portable cassette deck. Record player? Yes, FiiO makes one of those, too.

Clearly, this is an ambitious and adventurous company, so when it launches its first full-size music streamer, we can’t wait to have a listen. FiiO refers to the S15 as a ‘desktop high-res audio streamer’, but we aren’t sure what that actually means.

In the metal, it is a standard, full-width 43cm unit, the same as any conventional hi-fi product, and there isn’t anything in the feature set that screams out dedicated desktop audio use to us. The S15 doesn’t even have a headphone output to suit that purpose.

Design

What we have here is a generally well-equipped but fairly conventional music streamer, and as such, it does everything you would expect from such a unit. The FiiO S15 will play music files from servers attached to your home network or any memory storage connected directly into its USB-A socket. As expected, it can connect to your home network either wired or wirelessly.

The S15’s operating system is based on Android 12, and as such, it is possible to download any appropriate app from the Google Play Store. Our review sample didn’t have either Tidal or Qobuz loaded straight out of the box, but it was the work of minutes to get them downloaded and functioning.

The use of Android undoubtedly gives the FiiO a great deal of versatility compared to most conventional rivals, but its inclusion brings about some usability issues, too, as we will find out later.

Connectivity

There is plenty of connectivity here, mostly digital, of course. You will find a USB-C port on the front panel to connect a computer, alongside a USB-A socket for external memory storage. Look around the back, and there is another USB-A, the usual optical and coaxial inputs (and more unusually, mirrored outputs), plus an HDMI, HDMI ARC and a third HDMI socket that outputs an I2S digital signal to feed a suitably featured external DAC.

Then there is the less common AES/EBU balanced digital connection with separate sockets for both input and output. Two-way Bluetooth (aptX HD/LDAC compatible) is on the menu too. As for the analogue outputs, the S15 has two sets of stereo RCAs and a single stereo balanced XLR.

This FiiO can also work as a server. It has an SD card slot (a maximum of 2TB capacity) and can support an M.2 NVMe SSD drive (also a maximum 2TB capacity).

Add it all up and, in terms of features at least, there is little else we can reasonably ask for from a product such as this, bar the rather odd omission of a physical headphone output.

Take a look inside this FiiO streamer and you will find AKM’s flagship two-chip AK4191/ AK4499EX combo at the heart of its digital circuitry. The AK4191 handles all the processing while its partner is responsible for the actual conversion. The timing of the circuit is controlled by a pair of high-grade Accusilicon AS318B low-jitter femtosecond clocks. The S15’s analogue section is fully balanced to minimise crosstalk and noise levels.

Elsewhere, the power supply uses a custom-made, low noise 35VA toroidal transformer and four 4700uF ELNA capacitors in a bid to deliver a stable, pure feed to the audio circuits. The power feeds to the digital and analogue sections of the circuit are kept isolated to prevent unwanted interactions spoiling the sound.

Build & usability

General build quality is good, as you would expect at this premium level, though there are areas where this FiiO feels a little low rent. We like the crisp 7.84-inch full colour touchscreen display, and the S15’s aluminium casework feels pretty solid, but the sense of quality is let down by the rather insubstantial dual rotary controls. There is very little resistance and a bit too much wobble in their movement for our liking.

While we’re on the negatives, we don’t find the S15 pleasant to use. The Android operating system allows it to be extremely versatile, but it also makes the player feel clunky. There are slight hesitations in carrying out actions, and the touchscreen isn’t always as responsive as we would like.

Its user interface isn’t particularly intuitive, either, and even after a couple of weeks we still find ourselves wondering how to get to a specific setting or function on far too many occasions.

That isn’t the worst of it, though. The partnering FiiO Control app, the main way most users will interface with the product, is one of the poorest streaming apps we’ve come across in years. It is buggy, poorly designed and prone to crashing. Some instructions inexplicably come up in Chinese, and the placement of some of the notifications is occasionally awful.

It also looks like it is optimised for a smartphone screen, and so there are huge empty spaces when using our usual iPad.

We are shocked that a company that has so much experience with streaming products can produce such a sub-standard app and general user interface, and that is reflected in our rating for Build.

Sound

With that out of the way, we can move to the S15’s sound quality, and here it is more of a mixed bag. We spend plenty of time working through the FiiO streamer’s various sound and filter options until we feel that we’ve optimised the results as much as we can.

On the positive side, we think this FiiO makes a generally positive first impression and can certainly see it impressing on a short demo at a dealer. It also sounds pleasingly consistent across its digital inputs, including Bluetooth, which connects to our phone seamlessly.

The S15’s sonic character is smooth and full-bodied, delivering generous doses of warmth and weight that we think many will like. This is mostly an unfussy performer that tends to be kind to thin or aggressive recordings, while still offering a decent level of clarity.

Listen to something easy-going, such as Come Away With Me by Norah Jones or Sade’s Diamond Life, and you’ll find things to like; the FiiO’s tonal balance is decently even, and the midrange relatively clear. Voices come through with solidity, and there is a nice sense of boldness to the presentation. In a market where many manufacturers value agility over authority and natural warmth, the FiiO’s sonic character holds appeal.

However, its limitations soon start to show when we play a wider range of music. As we work our way from The Police’s stark but energetic Outlandos d’Amour through to TLC’s CrazySexyCool, taking in Beethoven’s Seventh Symphony and Coltrane’s A Love Supreme on the way, we can help but notice that the FiiO struggles to deliver the true essence of each musical performance.

It delivers a compressed sound that fails to convey the dynamic ebb and flow of the music properly. The track Roxanne from The Police is robbed of its rawness, while the TLC set sounds oddly sanitised, with the group’s punchy beats and passion-filled vocals lacking their usual verve.

Rhythmic drive isn’t conveyed well, with the FiiO unable to deliver the innate momentum of the music properly. The presentation sounds safe and undemanding, whereas the TLC recording demands punch and attitude. It doesn’t help that lows sound overly plump and poorly defined. Those after taut and tuneful bass definitely need to look elsewhere.

The S15’s limitations are thrown into sharp relief by the similarly priced Bluesound Node Icon rival. This Award-winning streamer has become a firm favourite at What Hi-Fi? Towers thanks to its blend of exceptional sound quality, operational stability and sensible feature list (which includes dual 6.3mm headphone outputs, by the way).

We use our reference Burmester’s 088/911 MkIII stereo amplifier and the ATC SCM50 speakers for much of our testing and comparisons, but also try both the FiiO and Bluesound streamers in a more price-compatible system of the Arcam A5+ amplifier and KEF LS50 Meta stereo speakers. Regardless of set-up, the Bluesound is streets ahead when it comes to sound quality.

The Node Icon is simply more transparent. It sounds considerably more insightful and offers far more in the way of resolution and precision. We can hear deeper into the mix and pick up on low-level details that the FiiO simply ignores; the reverb around a vocal or the acoustic clues that define the recording venue are more obvious. The TLC album is now fun to listen to, while A Love Supreme grips our attention and emotions from beginning to end.

Verdict

The FiiO S15 certainly impresses on paper and offers a degree of versatility that betters most of the competition. But given its premium price, that simply isn’t enough. We feel there could be a solid product here; the raw ingredients certainly seem present, but the S15 needs further development, as does the undercooked app. Until that happens, our money would go elsewhere.

Review published: 8th January 2026

SCORES

• Sound 2
• Build 3
• Features 5

MORE:

Read our review of the Bluesound Node Icon

Also consider the Cambridge Audio CXN100

Best music streamers: top network audio players tested by our experts