FiiO’s new M21 MP3 player is a sonic treasure for your entry-level listening pleasure

• Price, availability, and specs
• The best entry-level audiophile DAP on the market right now?
• It’s what’s on the inside that counts
• FiiO M21 in a word: Transparent
• Battery life
• What could use improvement
• Should you buy the FiiO M21 digital audio player?

The FiiO audio brand has made a name for itself by bringing high-quality audio products to market that have a long list of features, but most importantly, sound great — case in point, the new FiiO M21 digital audio player, or DAP. People are beginning to realize just how distracted we are in so many areas of our lives and are asking, “how can I [insert activity] with less distraction?”

Whether it’s a workout, a study session with lo-fi beats to power you through, or simply listening to your favorite songs and discovering new ones, all with fewer distractions, FiiO hopes their new DAP is the answer to that question.

Read on to find out if the FiiO M21 is the answer for you.

Price, availability, and specs

Released in 2025, the FiiO M21 DAP is available in two colors: Titanium Gold and Dark Blue with gold buttons. The portable music player can be found for $330 at various online retailers, including Fiio.com, Amazon, Aliexpress.com, and B&H Photo-Video.

The best entry-level audiophile DAP on the market right now?

“Low-cost” with flagship features

The FiiO M21’s list of hardware and software features is extensive. This could very easily be a few-page-long review to cover every hardware innovation and use case. There are DAPs with similar features that cost hundreds of dollars more. In the interest of making this review accessible to music enthusiasts and the “audiophile curious,” I’m going to keep this as accessible as possible.

Unbox the FiiO M21, and you’re greeted by a beveled anti-glare frosted glass back, textured aluminum alloy body, and a good-looking 4.7-inch 750×1334 IPS display that comes with a screen protector already installed, all wrapped in the included, color-matched silicone case. The unit appears to have a very sturdy build when viewed in the box.

Removing the device from the packaging, it has a great in-hand feel, thanks to the beveled edges. In addition to the included silicone case, FiiO sent a PU case to check out, which is a nice touch, and with more cases available from them, including one that makes your DAP look like a retro Walkman, you’ll have plenty of options for protective, fashionable carry. Looking around the device, you’ll find a 3.5mm single-ended and 4.4mm Balanced output on top. Both support line out, with the 3.5mm also supporting coaxial output.

The right side of the unit houses playback controls, while on the left side, you’ll find the power/sleep button, a volume rocker, a multi-function button, as well as desktop mode (D.MODE) and Hold switches. The bottom of the M21 has your microSD card slot that supports up to 2TB of storage, a USB-C 3.0 data/charging port, and next to that, a dedicated charging/power supply USB-C port that supports PD3.0 20-watt fast charging that will get you back to 100% from zero in an hour and a half.

It’s what’s on the inside that counts

Power and connectivity to spare

This section could go on for pages, labeling and explaining everything inside the FiiO M21. You get Qualcomm’s Snapdragon 680 processor that runs Android 13 and any apps you download, quite capably. Plus, with an eight-core processor running up to 2.4GHz with 4GB of RAM, it’s powerful enough for you to listen to lossless music files on high gain and surf the web, or crap-post memes simultaneously, if that’s your thing.

With that processor, you’ll also get Bluetooth 5.0 with support for aptX HD, LDAC, and LHDC, along with the basic codecs. The chipset also has support for both 2.4GHz and 5GHz Wi-Fi that supports DLNA, Airplay, Wi-Fi song transfer, and is Roon-ready.

For the first time on an entry-level FiiO DAP, you get a desktop mode. That second, dedicated USB-C charge port becomes a power pass-through that supports external power and saves you from wearing the battery down quicker. When connected to a PD3.0 charger, the 4000mAh battery won’t charge or discharge; a feature every good DAP and self-powered DAC should have.

Internally, powering the sound quality and output are four Cirrus Logic CS43198 DAC chips working in parallel, with a two-stage circuit design whose op amps and other hardware ensure enough clean power that you’ll have access to three gain levels, and an additional Super-High Gain when in desktop mode. For the full list of power outputs for that, see the spec chart.

FiiO M21 in a word: Transparent

Neutral, with excellent detail retrieval

Let’s get into what you came here for: the listening and daily use experience. I tested the FiiO M21 with a few headphones, IEMs, and TWS earbuds:

Overall, the FiiO M21 is a wonderfully transparent experience that brings audio to life with vivid detail and nuance. Actively listening using the 4.4mm Balanced port and medium gain with Sennheiser’s analytical flagship $1500 IE900 IEMs, I was able to hear details like the fingering of saxophone keys as they were depressed before the saxophonist blows the notes on Charles Mingus’ chaotic Jazz romp, Moanin’.

I felt like a “sonic sommelier” who’d just paired a decadent fine wine with a Michelin three-star meal. Layers of nuance, stereo imaging, and meticulous sound engineering came to life.

The transparency and detail retrieval of the M21 with the analytical IE900 had a beautiful synergy, but that transparency can also mean fatiguing treble. Listening to Art Blakey’s take on Moanin’ those harsh horns can be quite fatiguing at specific moments in the composition.

Active listening using Campfire Audio’s warm Mammoth IEM’s was a treat — I listened using both 3.5 mm and 4.4 mm jacks, and the amount of clarity, transparency, and nuance was outstanding. The stereo imaging was merely satisfactory, but this was more due to the Mammoths themselves than the M21’s output. With this pairing, you get a strong sense of the intimate soundstage, and you’re going to pick up on things like room tone and sound reverberation in the studio recordings. If it’s a live recording, those little details really come through and give a live feel to the music.

With everything I threw at the FiiO M21, my primary takeaway is that the level of transparency and detail retrieval is sublime. It is a “colder” listen than some DAPs in that the bottom end warmth isn’t hyped, so you’re going to get the music just as recorded. Some might call it a bit flat, but I can absolutely tell you that depends on how a song was mastered and the headphones/IEMs/TWS earbuds you pair the DAP with.

For example, The Roots’ Do You Want More?!?!?! is mastered with deep bass that had delightful extension and presence with all listening equipment I connected to. Skrillex’s Supersonic (my existence) still had its deep, dark rumble, but it just wasn’t as hyped as it comes off when played from a DAP or DAC with V-curve tuning. I always tell people that your headphones are more important than your DAP/DAC, and that is equally true in the case of the M21.

Case in point: listening to those songs with the excellent Noble Rex 5 TWS earbuds imbues those songs and others with more weight, more drama, more of that soul-stirring vibration without any need for the PEQ, which, by the way, does not work with Bluetooth earbuds.

The great news is that, with this DAP, you get excellent options for shaping the sound more to your liking through the robust ten-band parametric EQ. If you have the means to choose different listening gear based on your mood, the FiiO M21’s sound quality is so good that you can forgo the PEQ altogether and just use the headphones/IEMs/TWS earbuds that match your desired sound signature. Want more hype in the lows? Connect them to those headphones with the menacingly dark bass and sub-bass response. Rinse and repeat, across the frequency spectrum.

Battery life

And other experiences

The inclusion of a dedicated charging port that supports fast charging is a delight here. In 30 minutes, I charged the DAP from 53% to full. It will take approximately 1.5 hours to charge from 0% to full using the dedicated port and a PD3.0 charger. For analog or digital playback, I found roughly one hour of play via the 4.4mm port with medium gain and screen at max brightness drained approximately 20% of the battery.

Having both 2.4GHz and 5GHz WiFi makes streaming effortless. The M21 connects quickly, and throughput is fast and consistent. Bluetooth quality has been surprisingly solid, even with formidable atmospheric conditions. As much as I love Noble’s Rex 5 TWS earbuds, their LDAC connections to multiple devices I’ve tested them with has been finicky. The M21 has been the exception, with the Rex 5 connected using the Best Effort (Adaptive Bit Rate) playback quality option, having no issues with signal breakup. In my testing using Bluetooth, I found that one hour of play using LDAC with the audio around 70 steps of 125, drained the battery by 10%.

Depending on my connection type, volume level, and music genre, I found myself getting anywhere from 10 to 15 hours of playback. You’ll get more stamina out of the 3.5mm port, but the best audio quality comes from that 4.4mm port. Regardless, I was never concerned about battery life with the FiiO M21’s fast charging capabilities or the dedicated power port on tap.

If you don’t completely power down the device after use, my experience with battery standby was a 6% drain over 22 hours.

What could use improvement

Not a lot at this price

With solid sound quality, an extensive feature list, and good looks there isn’t a lot FiiO could do to upgrade the experience at this price. Since the M21 is running a customized version of Android 13 with a Snapdragon chipset, I’d like to see automatic brightness added to improve outdoor use under these bright California skies, as well as aptX Adaptive and LE Bluetooth with Auracast support.

As time goes on, I think Auracast will be an important feature for DAPs to have.

Should you buy the FiiO M21 digital audio player?

There is solid competition for the FiiO M21 in the form of the HiBy R4, Shanling M3 Plus, Astell&Kern Activo P1, and iBasso DX180. For the price, the M21 is not only one of the most powerful, but the best value of the bunch. The only factor that would cause me to consider any of those against FiiO is iBasso’s DX180 and its user-replaceable battery. Being able to pop a new battery in will increase the useful life of the DX180, but that’s it.

Personally, I’d say that at $329, the FiiO M21 is one of the best entry-level DAPs on the market today, so I can absolutely recommend it.