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Everything you expect from FiiO where specification and performance are concerned, with just a hint of operational instability that you don’t


  • Poised, articulate and engaging sound
  • Great specification and compatibility
  • Built like the proverbial


  • Occasionally less than perfect playback
  • Quite a chunky item
  • Not without competition

Key Features

  • Battery10 hours of battery life
  • Storage64BG memory (expandable by up to 2TB)
  • File support24-bit/384kHz and DSD256


FiiO, it’s worth reiterating, is on a bit of a roll. Where its most recent desktop audio equipment and over-ear headphones in particular are concerned, they’re fully competitive, good value for money and sufficient for their most obvious rival brands to sit up and take notice.

With the M23 digital audio player, FiiO (again) wants to take the fight to Astell & Kern in particular – this is not the most affordable FiiO DAP, but it’s more affordable than the cheapest A&K. So it’s either more FiiO sorcery or a bit of a false economy… 


The FiiO M23 digital audio player is on sale in the United Kingdom for £649. American customers will have to part with $699, while in Australia you’re probably looking at AU$1249, depending on exchange rates, although no official Australian pricing is available at time of review.

The M23 has a little competition at this price, of course – no least from FiiO itself. But it’s Astell & Kern that is the most obvious rival – its SR25 MkII goes for £699 and has plenty to recommend it. So the FiiO has its work cut out…  


  • Blue titanium or stainless steel finishes
  • 5.5in 720 x 1440 display
  • 137 x 76 x 18mm (HWD); 299g

You can look at it one of two ways: either the FiiO M23 is a purposefully hefty and substantial device, or it’s pointlessly large compared to your smartphone which, after all, does pretty much everything the M23 does. I guess a lot depends on whether or not you want to slip your nice new digital audio player into a pocket or into a bag.

FiiO M23 side controls
Image Credit (Trusted Reviews)

At 137 x 76 x 18mm (HWD) and 299g it’s certainly a palmful. It’s undeniably well made, mind you, and those pointed edges that might otherwise pose a threat to your pocket-lining or similar are smoothed off by the protective silicone case that comes with my blue titanium review sample – if you prefer the stainless steel finish that’s available as an alternative, it’s supplied with a leather case instead. 

There are sockets and/or controls on each of the player’s four edges, and the front surface is occupied almost entirely by a 5.5-inch display. It’s bright and crisp, as its 720 x 1440 (18:9) resolution suggests it might be, and there are plenty of options regarding font size, brightness and so on to be investigated in the player’s settings menu.  

FiiO M23 headphone inputs
Image Credit (Trusted Reviews)

The asking price dictates a degree of tactility as well as ergonomic good sense, of course. And in this respect, at least, the M23 does the business – where materials, build quality and finish are concerned, it looks and feels like a premium product. 


  • Twin AKM DACs
  • THX AAA 78+ amplifier architecture
  • 5500mAh battery

Of course, I knew before now that FiiO has a trowel and is not afraid to use it. And sure enough, for the specification of the M23 the company has laid it on thick.

On the inside, the M23 is powered by a big 5500mAh battery that’s good for over 10 hours of playback from a single charge. A dual-mode fast-charging system means extreme fast-charging (up to 30W) speeds are available if the battery level is very low – once the battery approaches its fully charged state, the M23 switches to a more usual fast-charging state. The result of this arrangement, says FiiO, is much-improved charging times with no impact on the long-term health of the battery.

Digital-to-analogue conversion is taken care of by a couple of AKM DAC chipsets – the AK4191EQ and AK4499EX operate in tandem, keeping the digital and analogue stages entirely separate and utilising DWA routing technology to keep the signal-to-noise ratio to an absolute minimum. And they give the M23 the ability to deal with digital audio files of almost every type (including MQA) up to a resolution of 24-bit/384kHz and DSD256.

The oomph is provided by FiiO’s latest fettling of the popular THX amplification design. Taking the THX AAA 78 (as used in its well-regarded M11 Plus and M11 Pro models) as a start-point, FiiO has refined the architecture to the point that it’s now called THX AAA 78+ – and can supposedly offer greater power output with minimal distortion and even more precision.  

FiiO M23 device history
Image Credit (Trusted Reviews)

These constitute just the headlines where internal hardware is concerned. FiiO is prepared to talk (at length) about its unified hi-fi audio architecture, four-stage 20-rail power supply, 28 high-capacity polymer tantalum capacitors, bespoke Digital Audio Purification System and plenty more besides… but by now the broad point is surely made. FiiO has never been anything other than profoundly serious where its digital audio players are concerned, and if the M23 fails it won’t be for lack of engineering effort.

Getting the sound out can be done a couple of different ways. Wired headphones can use either the 3.5mm unbalanced or 4.4mm balanced outputs on the top edge of the player – of course, these sockets can also be used to hard-wire the M23 to an amplifier or what-have-you. And the 3.5mm socket is hybrid, also acting as a digital coaxial output in case you want to bypass the M23’s DAC circuitry.

There are also wireless possibilities for both getting audio information on board and getting it out again, of course. Dual-band Wi-Fi is on board, and the FiiO can both transmit and receive using Bluetooth 5.0 – and in each direction, it’s compatible with SBC, AAC, aptX HD and LDAC codecs

On one edge of the chassis there’s a power button – it’s edge-lit to indicate the size of digital audio file the player is dealing with. There’s also a multifunction button, the specific function of which is simple to define. And in between there’s the volume control arrangement FiiO has lately become so fond of: it’s a carbon-fibre strip/rocker, and you can either slide a finger up or down, or press either end to make your adjustments. 

FiiO M23 Bluetooth codec
Image Credit (Trusted Reviews)

On the other edge there’s a group of three buttons taking care of play/pause, skip forward and skip backwards. There’s also a hold switch to prevent any unsolicited actions being carried out, and a switch to put the M23 into D-mode. D-mode is desktop mode – when it’s switched on, the player is completely powered by an external power source plugged into one of the USB-C sockets on the bottom and the battery is bypassed altogether, so you can use your M23 as desktop equipment without worrying about the effect you’re having on the battery. The other USB-C socket is for data transfer, and allows the FiiO to act as a USB DAC.

Like all FiiO digital audio players, the M23 uses a breathed-on version of Android as an operating system – in this instance, it’s Android 12. A Qualcomm Snapdragon 660 processor ensures the FiiO is fast and responsive in its interactions, and some careful reskinning means the operating system doesn’t eat into the 64GB of internal memory all that much. And besides, the microSD slot on the bottom of the player is good for cards of up to 2TB – which should, in any realistic circumstance, be plenty.

Sound Quality

  • Balanced, open, positive sound
  • Detail and dynamic in equal measure
  • Some mild operational glitches

FiiO offers a fair amount of scope for end-user adjustment where the sound of the M23 is concerned – using the touchscreen you’re able to adjust the EQ frequency point, gain and bandwidth, fine-tuning the response curve to suit your preferences.  

No matter how you fiddle around the edges of the audio quality here, though, it seems unlikely in the extreme you’ll be able to prevent the M23 sounding direct, informative and thoroughly musical in any and every circumstance. 

During the course of this test I listen to it via a pair of Bowers & Wilkins Px8 connected wirelessly and a pair of Sennheiser IE 900 connected via the 4.4mm balanced output. I listen to music streamed from Qobuz and TIDAL, as well as music loaded directly onto the player’s internal memory. And at no point does the M23 sound anything less than poised, dynamic, lavishly detailed and endlessly listenable. 

FiiO M23 file formats
Image Credit (Trusted Reviews)

A 24-bit/96kHz FLAC file of In the Moon House by Szun Waves illustrates these points nicely. The M23 sounds open and organised, with a pleasantly neutral tonal balance and a deft way where integration of the frequency range is concerned. There’s tremendous dynamism to the piano, a lot of variation in the harmonics of the instrument, and an absolute stack of detail revealed when the saxophone abstractions and clattering percussion join in. The recording sounds unified, the result of performers responding and reacting to each other, rather than of individuals doing their own individual thing. It sounds like a performance.

Switching to a DSD64 file of Stevie Wonder’s timeless Innervisions allows the M23 to show what it’s got where low-frequency control, rhythmic expression and midrange fidelity are concerned. And it’s safe to say the FiiO has got plenty – it communicates in the most eloquent way where the forward-in-the-mix vocal is concerned, punches through the low-frequency information with both determination and momentum, and keeps a close eye on the transient information at the edges of the recording. Again, the sense of engagement and performance is tangible.

At every turn, in fact, the M23 is deft and muscular, forthright and subtle, detailed and dynamic. They seem perfectly content to engage with any type of music you care to listen to, and are even prepared to slum it if you decide you want to hear some sub-16-bit/44.1kHz content. It seems almost impossible to throw it out of its brisk, confident stride.

FiiO M23 playback
Image Credit (Trusted Reviews)

Or, at least, it’s not possible to do so via the content you choose to listen to. There are, though, a couple of operational glitches that become apparent during the course of my test that, although minor, serve to both aggravate and to undermine the impressive nature of the M23’s performance somewhat.

The M23 will pause, unbidden, at random – not very often, but enough to become apparent. It can sometimes chop into the first second or so of a digital audio file, starting playback from just slightly further forward than 0:00 of the recording – when this happens, it’s always when starting some newly cued-up content. Once an album or playlist is playing, the M23 behaves as it should, but switch to a different stream and the glitch will sometimes manifest itself again. 

Obviously these are far from fatal flaws. But equally obviously, they’re not what anyone is expecting from their pricey new digital audio player.

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Should you buy it?

You want an engineering tour de force that results in some beautifully judged audio quality

The pains that FiiO has gone to where the M23 is concerned are apparent in the way it sounds

You feel entitled to flaw-free playback

I mean we all feel entitled to flaw-free playback, don’t we? But it’s not always on offer here…

Final Thoughts

I needed no convincing where the idea of a dedicated digital audio player is concerned – but nevertheless it’s always good to have one’s biases confirmed. The FiiO M23 is the perfect riposte to anyone who thinks their smartphone is good enough to take care of the business of music playback.

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How we test


How much storage can I add to the FiiO M23?

You can add microSD storage up to 2TB.

Full specs

Screen Size
Storage Capacity
Size (Dimensions)
Operating System
Release Date
Audio Formats
Touch Screen

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