If you don't know FiiO, then you haven't been paying attention. The Chinese brand has been turning out audio products (DACs, headphone amps, DAPs like this one, headphones, you name it) for nigh-on for two decades now and has seen its reputation and sales grow exponentially. Credibility is not something that this company is short of.

The M23 is the latest in its burgeoning range of digital audio players. It sits in the lower middle area of that range, where it is positioned to go up against Astell & Kern's entry-level A&norma SR25 MKII. In fact, I'm tempted to say that FiiO is the only significant company standing between A&K and DAP ubiquity! As has become established FiiO practice, this little player is exceptionally well kitted out. It's difficult to identify an area where the designers have done anything less than their utmost.

For instance, FiiO has taken the well-regarded THX AAA 78 amplification that was used to such good effect in its M11 range of DAPs and breathed on it to deliver THX AAA 78+. Augmented by a 4-stage, 20-rail power supply and 28 high-capacity polymer tantalum capacitors, it is designed for minimal distortion and class-leading precision. It's also able to supply clean, stable power no matter the fluctuation in demand.

This amplification architecture sits downstream of a couple of AKM DAC chipsets. The AK4191EQ and AK4499EX operate in tandem here, separating the digital and analogue stages and utilising 'DWA routing' technology to keep the signal-to-noise ratio to an absolute minimum. The M23 can deal with digital audio files of every worthwhile type, including MQA, up to a resolution of 24-bit/384kHz and DSD256

The M23 will drive both wired and wireless headphones, of course, and the top of the machine features 3.5mm unbalanced and 4.4mm balanced outputs that can be used either for connection to headphones or to external audio equipment such as amplifiers or powered speakers. The 3.5mm socket is, in fact, a hybrid output that can also be a digital coaxial output if you're fortunate enough to have access to a DAC that is even more capable than the unit's built-in one. Wireless connectivity is via Bluetooth 5.0, and the M23 can act as both a transmitter and a receiver. It is compatible with SBC, AAC, aptX HD, and LDAC codecs in either direction.

It's no hardship to get what you want from the M23, either. Like all FiiO DAPs, its operating system is based on Android – version 12 in this instance. A Qualcomm Snapdragon 660 processor means the OS is fast and responsive, and FiiO's finessing of Android 12 means it doesn't eat too far into the player's 64GB of internal memory. The provision of a microSD slot on the bottom of the machine that's able to accept cards of up to 2TB doesn't do any harm either. The 720x1,440 touchscreen interface is 5.5 inches, which is plenty big enough for even those of us whose fingers are larger than cocktail sticks to get what we want swiftly and reliably.

The selection of physical controls arranged around the edge of the M23 is equally well-implemented. Biggish buttons, all positive in their actions, take care of power on/off, volume up/down, play/pause and skip forwards/backwards. There's also a 'hold' button to prevent inadvertent operation, a user-definable multifunction button, and a slider to engage 'D-mode' – that's 'D' for desktop. One of the M23's two USB-C sockets is for data transfer, or when the player is in use as a desktop DAC – and when 'D-mode' is enabled - the player is powered by an external supply plugged into the other USB-C slot. This way, desktop use has no effect on the FiiO's battery whatsoever.

The battery itself is a 550mAh number that is good for around 10 hours of playback from a single charge. A dual-mode system means extremely fast charging (up to 30W) is available if the battery level is very low, but once the battery approaches its fully charged state, the M23 switches to a more usual fast charging rate. The result of this system, says FiiO, is much-improved charging times with no impact on the long-term condition of the battery. So yes, just like I said, FiiO knows perfectly well how to go to town.

In use, my review sample had a random operational quirk – it would sometimes pause music playback when switching audio content. Just very occasionally, it would chop into the first fraction of a second of playback, meaning the selected music didn't play from the very beginning but rather a split-second in. This manifested itself only when switching from, say, music streamed via somewhere like TIDAL to content stored on the player's internal memory. It didn't happen every time, by any means, I must add.

I found little reason to play with the frequency curve via EQ frequency point, gain, and bandwidth; in all honesty, little good came of it. At best, it makes the FiiO sound different rather than in any way better—which was true no matter what headphones I was using. It turns out that FiiO's engineers know better than I do.

THE LISTENING

The new M23 sounds excellent. It's a brilliantly complete and coherent listen, able to bring even those recordings you've heard numerous times before bounding back to life. For instance, I recently invested in a 24-bit/192kHz download of the 2017 remaster of David Bowie's Low. Heard through a pair of Sennheiser IE900 in-ear monitors connected to the M23's 4.4mm balanced output, the effect is not so much 'like hearing it for the first time' but more like 'hearing it after it has been freshly laundered'. As a recording, it's quite processed and heavily treated before it gets anywhere near being mastered. The M23 doesn't attempt to hide – or indeed overplay – this fact but instead hands over an unexpurgated version packed with detail. Open and spacious in its soundstaging, the FiiO offers the sort of insight through the midrange that makes it sound thrillingly direct.

Despite being a recording of considerably different emphasis, it's a similar story when switching to a 24-bit/96kHz Qobuz-derived file of Aretha Franklin's Spirit in the Dark, streamed wirelessly via aptX HD to a pair of Bowers & Wilkins Px8 over-ear headphones. Detail levels are almost vertiginously high – no occurrence in the recording is too fleeting or too minor to escape this player's attention. Its overall tonality is winningly neutral – which means that it is as warmly organic and overtly 'analogue' in its emphasis as the original recording. Low-frequency presence is substantial but never overblown. Instead there is great bass control in evidence alongside a lovely, naturalistic way with rhythmic expression as a result. The balance of the frequency range is even and smooth, and at the top end there's as much bite and shine as is needed.

It's in-between though, that the M23 fully demonstrates its understanding. David Bowie is a committed and characterful singer of course, but he's no Aretha Franklin. The FiiO lets her communicate with stunning articulacy, allowing all her technique, character and attitude to shine. If you have hair on the back of your neck, be prepared for it to rise.

In every other meaningful respect, too, the M23 is never less than impressive. It has the sort of dynamic potency that lets it put significant distance between Daniel Hope's solo violin and the massed efforts of Zürcher Kammerorchester during Saint-Saëns' Danse Macabre, and the attention to harmonic variation that makes that solo violin beautifully reproduced. And if it's sheer visceral attack that you're after, once through Okay, Let's Talk About Magic by F Buttons is enough to let you know that the FiiO can handle itself in a fight.

THE VERDICT

I am not in the least bit surprised by the performance of the new FiiO M23. It's an extremely capable device when considered on a pound-for-pound basis. The quoted specification hints at how capable it might be, but once you've heard your favourite music via this while you're out and about, your smartphone will never sound satisfactory again. As it stands, then, the FiiO M23 is a must-audition for those who appreciate their music on the move.

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