FiiO M21 review

The demise of the iPod Touch left a sizeable gap in the portable audio landscape. Sure, there have been a number of premium music players released in the years since the Touch died in 2022 to keep hi-res connoisseurs happy, mainly coming courtesy of South Korean brand Astell & Kern, but there are far fewer offerings for those seeking decent portable performance in a more affordable package.

A&K's sub-brand Activo took a swing at the more budget side of the spectrum with its Activo P1 player (tested at £399 / $430), but disappointing sound and a cheap-feeling build meant that it fell short of the mark. Sony’s NW-A306 (£349 / $350 / AU$499) gave it a good go a few years back, even if irritating quirks meant that it fell short of a five-star accreditation.

That’s the particular nut which FiiO is attempting to crack with the M21 (£279 / $329 / AU$529), a far more competitively priced alternative to Astell & Kern’s big-money offerings, which seeks to bring together flagship hardware and charming retro aesthetics for under £500 / $500.

Build

The FiiO M21 leans towards the chunkier end of the portable music player spectrum. Around the size of a slightly elongated deck of cards, it’s not a burly colossus, and you’ll still be able to slip it into all but the skinniest of skinny jeans without ripping a hole in your denim. But it’s a bulkier item than most of the slimline iPhones and Android smartphones to which we’ve all become so accustomed to holding in our hands.

Admittedly, we’re operating in a world of predominantly plastic and rubber here rather than the sleek, weighty metals in which the more premium Astell & Kern A&norma SR35 might be clad, but the FiiO is playing to a far more budget-conscious audience. For this price, it’s hard to take issue – from the scratch-resistant solidity of the back panel to the reasonable quality of the plastic buttons, we can find few reasons to feel actively shortchanged.

​The M21’s 4.7-inch touchscreen naturally takes up most of the space on the unit’s fascia, a screen which we find generally provides a tactile, responsive experience. It doesn’t have the absolute immediacy of a typical modern smartphone screen, and occasionally we find that the M21 struggles with commands requiring pinpoint precision (such as using Tidal’s track slider), but on the whole, our testing experience is still a positive one.

The FiiO player sports its fair share of buttons on either side of the unit, offering up/down volume controls on the left flank housed above a multi-function toggle which can be set to control a range of tasks, including switching filters, toggling listening modes or locking the screen.

On the right-hand side, a play/pause button is sandwiched between a skip track toggle and a previous track button, while the top of the unit sports 4.4mm balanced and 3.5mm headphone outputs.

Features

FiiO’s well-priced portable music player harnesses the power of an octa-core Qualcomm Snapdragon 680 chipset to deliver a quick and responsive Android OS performance. This does mean you get full access to Google and can download music apps (and others) via the Play store.

The M21 also grants 64GB of internal storage, although if that isn’t enough to house your extensive collection of Beethoven sonatas, you can expand this to a healthy 2TB via the microSD slot.

At the heart of the player’s performance are four Cirrus Logic CS43198 DAC chips arranged in a matrix configuration, an architecture designed to reduce crosstalk and noise in pursuit of a "clean and dynamic sonic profile". ​

The FiiO M21 is capable of handling hi-res PCM files up to 32-bit/768kHz alongside DSD512 and full MQA decoding, while SBC, AAC and LDAC Bluetooth codecs are all on the menu. We envisage that most users will use a dedicated hi-res player such as this with a pair of wired headphones rather than relying on a wireless connection, but the FiiO’s stable, easy-to-access Bluetooth powers are nice to have all the same.

Like many of its FiiO siblings, including the four-star M23, the M21 offers a handy 'desktop mode' so you can use it as a DAC/amplifier for your laptop-based listening. When connected via USB-C to an external power source, the FiiO bypasses its onboard battery to deliver up to 950 mW per channel to drive a 32-ohm headphone load without straining the player’s internal juice pack.

The M21 also offers a ‘Pure Music Mode’ which essentially closes all other apps and background operations to run exclusively on the FiiO Music app, aiming to reduce system interference and provide a clearer, cleaner experience as a result.

Speaking of batteries, the M21 claims to offer a healthy 15 hours of battery life when driving a standard pair of headphones using the 3.5mm output, though that will drop to around 11.5 hours for listening through the balanced output. Those aren’t bad numbers, even if they don’t get close to the 30 or so hours granted by the price-comparable Sony NW-A306.

Sound

We wouldn’t expect a player at this price to be charged with feeding a megabucks pair of audiophile headphones. Pulling out a set of Yamaha YH-5000SE would be straying into overkill, so we perform the bulk of our testing with the well-priced but supremely capable Beyerdynamic DT 990 Pro X (£189 / $199 / AU$399) and the ever-dependable Grado SR325x (currently £247 / $295 / AU$425).

What we discover is a portable player of considerable talent. With Tidal primed and loaded, we start our listening off with some smooth, sun-soaked folk courtesy of Waxahatchee’s Right Back To It, and sit back and delight in how the FiiO ably communicates the rich textures of the track’s twangy, laid-back guitar. The central vocal performance complements the guitar beneath, offering sufficient textural insight to track Katie Crutchfield’s vocals as they move from resonant mids to soaring highs.

Things get a little more complicated as we switch from summery Americana to a full-fat orchestral score – yes, it’s time to break out some Hans Zimmer and boot up The Battle from the Gladiator soundtrack. There’s a lot going on across that epic 12-minute runtime, rising from low horns and occasional percussive rumbles to a tidal wave of orchestral swell, but the FiiO has the clarity and cohesion to hold everything together, even when things get tricky.

The portable player’s cohesion is wedded to a smooth, weighty balance that still packs a punch when required. The M21 happily belts out Alice In Chains’ Lesson Learned with appropriate vigour, granting the tune’s meaty central guitar riff plenty of bite and texture without getting carried away. This is the sort of track that can sound sloppy or ill-defined, especially when the volume dial moves northwards, yet the M21 is insightful enough to stop those driving, crunchy riffs from sounding like a single block of ill-defined noise.

Our disposition toward the FiiO improves further when we switch Pure Music Mode on and dig out 24-bit/192kHz FLAC renditions of Tom Waits’ Rosie and Muse’s Panic Station. There’s a clear step up when we’re operating in a dedicated audio profile with appropriately decent files to play with – everything is sharper and more defined, with the M21 showcasing a nimbler, clearer profile than when operating in its standard, busy Android mode.

This is all sounding rather positive, especially for a player that will only set you back £279 / $329 / AU$529. Yet the more we listen, the more we realise that we’re enjoying a pleasant listening experience rather than a wholly engrossing one.

That lack of true musical engagement comes from the fact that the FiiO doesn’t quite have the rhythmic chops to really make our music shine. While Panic Station is clear and crisp in its delivery, that underlying propulsion pushing the track forward isn’t communicated as enthusiastically as we’d ideally like, and while the rendition doesn’t feel sluggish, it doesn’t clip along with the vigour we crave.

Dynamics, too, leave a good deal to be desired. The Battle may be well organised and fleshed out with rich detail levels, but it lacks the feeling of ever-building drama to make us feel as adrenalised as a Roman legionary about to face off against a horde of hairy-faced Germanic tribesmen. The portable player’s dynamic presentation is full-bodied yet frustratingly flat, failing to communicate fully the ever-building dread and drama of Zimmer’s masterful composition.

No matter the quality of the files we feed the FiiO, those limitations remain. That said, the M21 is perfect for when you’re seeking out a rounded, detailed and ultimately undemanding listen, and while it won’t necessarily stir your soul, there’s still plenty of musical enjoyment to be found.

Verdict

We’ve been crying out for more affordable portable music players with sufficient sonic chops, and there’s no denying that FiiO’s likeable M21 is a fine effort. It isn’t perfect, but you’ll have to spend a good deal more if you want to get something significantly better. For this sort of money, the M21 is a pleasing portable performer.

Review published: 4th February 2026

SCORES

• Sound 4
• Features 5
• Build 4

MORE:

Read our review of the FiiO M23

Also consider the Sony NW-A306

Read our Astell & Kern A&norma SR35

Best portable MP3 players: our expert picks of the top hi-res music players