FiiO M21 Digital Audio Player

Great-sounding player with a few software limits

𝗦𝗼𝘂𝗻𝗱 𝗮𝗻𝗱 𝗕𝘂𝗶𝗹𝗱: The M21 sounds great and feels really well built. It does exactly what I want a dedicated music player to do, and it's become my go-to for listening.

𝗕𝘂𝘁𝘁𝗼𝗻𝘀: The hold and charge-through buttons are awesome. Hold locks the controls so nothing gets pressed by accident in a pocket or bag, and charge-through is great when it's plugged in for long listening sessions. They're small touches, but they show it was designed by people who actually use their players.

𝗦𝗼𝗳𝘁𝘄𝗮𝗿𝗲: This is my main complaint. FiiO pushes its own EQ and hardcodes a lot of how audio is handled, so you get less freedom than you might expect. If you like using your own EQ setup or third-party apps, that can be frustrating.

𝗦𝗰𝗿𝗲𝗲𝗻: The screen is on the lower-resolution side. It's noticeable, but not really an issue on an audio player, since you're mostly just browsing and controlling your music.

𝗢𝘃𝗲𝗿𝗮𝗹𝗹: If you want a solid dedicated player and don't need full control over the software, the M21 is a great pick.

Gunsmokenyc

August 2, 2026

Fiio M21

I have to say I’ve tried several types of DAPS. I have to admit that this player Is one of the most best sounding DAPS I’ve ever heard. Paired it with my FIIO FT1’s using 4.4mm balanced input after a full week of breaking in my Fiio’s FT1’s the sound was night and day. I also tried my LETSHUOER Astralis 15.5mm planar IEM’S also using a balanced 4.4mm connection and the sound and soundstage was outstanding drove both headphones and IEM’S without a sweat. Battery life testing on Bluetooth with a full battery lasted over 14 hours of continuous play.

When using the 4.4mm balanced connection using desktop mode and a pair of cans in my case my FT1’s from Fiio I got about 8 hours of use.

Great touch screen and size , and easy to use interface.

Why spend more when you can have the an excellent DAP and sound quality your looking for at a fraction of the cost.

The materials used are premium flagship especially the snapdragon 680 processor and 4 DACS. Expandable storage upto 2T.

You get a ton of features with the M21 and you can customize it to your listening needs. Desktop mode for more power to drive those cans or it can also serve as a laptop/PC DAC with certified Hi-Res audio and Hi-Res audio Bluetooth streaming.

I am very satisfied with the performance of the device and what features the Fiio M21 offers. I recommend USB Audio Player or Poweramp player for android users for more customization options especially with adjustable EQ settings you can take it to another level with your sound. I have tested both with excellent results.

Don’t think twice grab yourself an M21 you will not regret it butter smooth. Lastly for Micro Sd cards listen closely you need at least v30 u3 A2 memory card for best results when storing FLAC or DSD files for best read and write speeds and performance. I have a Lexar Micro SD card 512GB V30 U3 A2. Perfect match for the M21 and works perfectly.

Great job Fiio on this budget powerhouse DAP 🙌

Versatilidad de funciones y Fidelidad

Compre el fiio m21 para escuchar apple music, música sin compresion, y es una maravilla de lo q es capaz este reproductor.

En cuanto a su android 13 es muy fluido, la pantalla se ve nítida y bien definida.

La reproducción de la música es de alta fidelidad.

Lo escucho fundamentalmente en dos formas.

Una en mi cadena de apple music/ topping dac x usb/technics SU-g95.

Y en auriculares, un hifiman sundara con 3.5 mm y 4.4mm y no tiene problema ni en fidelidad ni volumen.

También funciona con Bluetooth sin inconvenientes, aunque prefiero la fidelidad del cable

En ambos casos la reproducción de sonido es de excelencia.

Y en cuanto a energía se puede usar con su batería interna o en su modo escritorio sin usar su batería para no desgastarla, eso se puede hacer de 2 formas, con un cargador de celular a la corriente o con una batería externa o power bank si se lo quiere usar en movimiento.

Es un aparatito pequeño y maravilloso!!!

Why the FiiO M21 Became My Most-Used Music Device

I waited about two months before writing this review because I wanted to evaluate the M21 as a daily-use DAP rather than form an opinion after a weekend of listening.

My typical headphone rotation includes the Ikko Obsidian OH10 IEMs, HiFiMan Sundara (2020 revision), good old Sennheiser HD 600s, and Beyerdynamic DT 770 Pro Xs.

A few out-of-the-box changes I made were swapping the stock launcher for Niagara Launcher and replacing FiiO Music with USB Audio Player Pro (UAPP). The default launcher is perfectly usable, and FiiO Music will likely satisfy most users, but UAPP really helped the M21 feel like a polished daily driver.

First impressions were excellent. The build quality is outstanding, and the blue-and-gold styling gives the player a distinctive look without feeling flashy. Compared to my classic iPod, the M21 is definitely chunkier, but not uncomfortably so. The buttons have a satisfying tactile feel, the dual USB-C ports and microSD slot are easy to access, and having both balanced and 3.5 mm outputs is appreciated.

I also picked up the optional Cassette Case from a third-party retailer and absolutely love it. If you’re considering one, I highly recommend it. It completes the aesthetic of the device, and the automatic cassette-mode interface is surprisingly charming. Most of the time I find myself using the player in this configuration with shuffle enabled.

As for sound quality and power delivery, the M21 has been consistently impressive. The DT 770 Pro X and Ikko OH10s perform beautifully from the single-ended 3.5 mm output, delivering a clean, energetic presentation with plenty of headroom. Compared to my K5 Pro ESS, the M21’s presentation feels a bit more lively and engaging, though never in a way that becomes fatiguing or exaggerated. Of the available DAC filters, I consistently preferred the Slow Roll-Off Minimum Phase setting.

For more demanding headphones such as the Sundara and HD 600, balanced output becomes much more beneficial. With balanced cables, the M21 drives both confidently. I haven’t encountered anything in my collection that truly pushes the device to its limits, although the Sundaras come the closest.

Battery life has been respectable and largely depends on how the device is being used. With efficient headphones like the OH10s or DT 770 Pro Xs through the single-ended output, I regularly see around 10-13 hours of playback. Balanced operation naturally consumes more power, but even then I typically get between 6-8 hours, which has been more than adequate for my listening habits.

Overall, the M21 is remarkably impressive for its price point. Yes, FiiO offers more powerful players higher up the lineup, and those devices carry price tags to match. But when it comes to value, performance, and everyday usability, the M21 feels like an understated champion.

The best compliment I can give it is this: I don’t think about it.

It gets out of the way and lets me enjoy my music. In many ways, that’s what made the iPod great in its day, and it’s what makes the M21 great now.

Best impulse buy ever.

Im loving this thing, got me back off of spotify. The new pod update is pretty cool for that old iPod functionality and feel. The player has indicator lights to let you know sound quality as well as an on screen quality display. The volume limiter allows for an extra %20 and honestly it’s probably much more. I cant turn it past 105% without my ears tingling on most music. There is room for improvement on the organization side, more options for sorting by meta would be nice.

This Music Player Can Replace A Full Desktop System

I've had the Fiio M21 for almost 3 months now. I bought it to replace my desktop system, which included a large audiophile headphone amp and an equally large audiophile music streamer, all controlled by a 10" android tablet. I wanted something that I could move around more easily, and did not need power cords. Most importantly it had to be able to drive my 300 Ohm headphones with proper authority. This Fiio ticked all the boxes. The Android interface lets me install and use all my music apps/services. Everything plays in bit-perfect quality. And the Desktop Mode and Super High Gain settings are designed for "hard to drive" headphones. Beyond that, Super High Gain can be powered by an appropriate external power bank, so no power cords needed. And it works. While the 300 Ohm phones play plenty loud using the normal High Gain Mode with internal battery power, switching to Super High Gain with outboard power makes the sound noticeably fuller and richer. Same performance as I get from my desktop system. I was surprised that my 40 Ohm headphones also play with more authority using the extra gain. I couldn't be happier. As you can see in the photo the whole system fits on a tiny side table which hides behind a chair when not in use and is easy to move out to the balcony for summer listening. Though I'm not much for on-the-go listening, I do expect to take the M21 along on an upcoming flight (without the power bank). It works really well with my IEMs too.

Andrey Marquart

March 21, 2026

Huge battery issue

I hate to give this 1 star as with the cassette case it is absolutely beautiful and so nostalgic. Unfortunately it has a major issue, battery life. After a few months of owning it started to drain battery so fast even when not being used. To the point where it will run dead in a day or two even when not in use. Never had this issue with any other device. Shame as I love it but it's barely useable as everytime I want to use it it's usually dead

It was well worth the purchase until it stop

I already own a JM21, but decided to upgrade to the M21. It takes everything great about the JM21 (easy to use IU, portability, sound quality) and improves upon it. The IU is a tad bit snappier, and the build quality is very robust. It's a little thicker and heavier than the JM21 but still portable/pocketable. Great piece of tech for music lovers.

*2/25/2026. After owning the unit for 2 weeks, it started giving me a random “USB Access Prompt” notification that loops over and over and makes the unit impossible to use. It also will no longer hold a charge because of an addition notification of “battery temperature is too low”. After extensive googling, and following all possible troubleshooting steps for the issues. It still will not charge past 3% and it still gives me the USB Access prompt loop. Sending the unit back as it’s defective

0:09

Unbelievably great

You will not be disappointed… I love music and this is absolutely amazing , I plug it into a 4.4 to rca to my amp , I listen to it at the gym , I play it Bluetooth to my Av reciever , I download music on it , I bought a remote they make for it, the cassette case, the sound is sooo good it sounds better than my Eversolo dmpA6, everyone I show this to is amazed . I had to write this review because fiio thought this product through so well and didn’t miss anything. I bought a very expensive sd card and that was the bigger expense . It’s fun and it’s quality..you can go in the mile hole on DMPs and look at astell and kerns etc.. but they are not as universal as this unit.

Lou

January 7, 2026

Fine DAP

Excellent snappy UI unlike Sony DAP's. I've had the unit 4 months and am still amazed at what it can do for the money. No problems with powering your higher impedance headphones (eg 300+). It's not very physically heavy but plays as such. Just get it even if you're an audiophile....lol... It's versatility is worth it.

M21 is Not Ready for PrimeTime Sales

This FIIO M21 is NOT ready for prime tme. The screen constantly jitters which makes it very difficult for the user to make any selections. I tried resetting the software to the initial settings and rebooting with no success. In my opinion, there appears to be an intermitent hardware problem. If the unit is left alone, it wll eventually get the screen steady to where you can operate the unit. But if you hit any button, the constant screen jitter will return. The unit costs $330 (not including tax). I returned the defective FIIO M21 unit before my 30 days for a full refund. I do NOT recommend the FIIO M21 until they can fix this screen jitter problem.

Doesn't index WAV files

I recently ripped about 18,000 tracks (via Brennan B3) from CD to WAV files. I was hoping to find a player that could recognize the WAV minimal tagging and index them appropriately after downloading to a microSDXC card. I first tried the Sony NW A306 and found that it wouldn't index the WAV files which are indexed by ARTIST/ALBUM/SONG. I then tried the FiiO M21, and it couldn't do it either. And not only that, the Fii0 puts in a Chinese character placeholder. See my photo of the Beatle's Come Together from Abbey Road. The form factor of the FiiO is much bulkier than the Sony, so I'm returning the FiiO and keeping the Sony.

It handled the MP3 and FLAC files I had well, so if you primarily have those files, you should be OK with this player. But as the photos show, form factor (in my mind) favors the Sony. Even though the Sony is more expensive

Beautiful rich sound!

I used to use my iPhone 6 connecting to my boombox listening to music. Now I use Fiio M21 to connect, the sound is amazing! Had a little trouble charging initially, almost returned it. One last look at the guide, I found the D-Mode for desktop switch on the left hand side was switched on by mistake; which prevents charging. Switching it to “Off” solved the problem. Add a little more info, Last couple of days the screen flashed crazily to the point of constantly turns itself off WiFi. Searching on Google for a solution, I did what is suggested, to clear history, saved items and cache, then pressed on the power button for 10 seconds and finally turned it off. This morning everything was back to normal, very happy, love to listen to music with this, the rich sounds are soothing and nurturing.

The device screen flashes a lot in hot days, so, I put an ice pack wrapped in a wash towel underneath the device, no more flashes!

Keep brightness to a minimal and put it on a covered ice pack, all problems are gone!

0:33

koogz

October 16, 2025

This is my favorite of the many I have tried.

This was one of several DAPs I have owned, and it is better than any of them overall as a great player.

- Desktop Mode (Pass through power) saves your battery life

- Form factor is really great and solid

- Software and PEQ works great

- Feels great in hand

- Love the sound it makes (Warmer than the rest)

- Compliments my Xenns Mangird Tea Pro IEM and FT1

- Casette tape mode (see video) Awesome, nostalgic) Really fun!

Negatives

- Display had an anomaly on the bottom (replaced the unit)

Other units tried

Hiby R6 III 2025

- Got pretty hot for me, cannot use A-Amp)

- Battery life was bad AB amp was pretty good

- Construction was wow

- Volume Button was great (I miss that)

- Software PEQ, MSEB was really great

- Plugins galor (System wide)

Hiby R4

- Great price

- Cheap-ish in spots with plastic

- No desktop mode

- Software same as R6 which is a plus!

- Cool style and very Cyber

iBasso DX180

- Pricey for what you get

- Amazing construction

- Sharp Edges

- Volume wheel was cool and you could control it

- Display is super bright 1080p

- Sound was pretty good

- No desktop mode

- Replaceable Battery (I'm a technician, I can replace anything on anything)

0:30

Calidad inmejorable!

Estoy muy satisfecho con este artículo, es EXCELENTE!

FUN SOUND, Amazing for Closed Backs! decent for OpenBack

I got this because I wanted a more intimate and special bond with my music when am on the go, rather that be on walks or visiting family. I also have been a bit tired using external amp/dacs connected to my phone. Carrying two bricks in my hand is never fun. The sound of the Fiio M21 by itself isn't anything memorable, very neutral sound, nothing exciting, especially compared to my Ifi Hip Dac 3. Where the M21 shines an where I fell in love with it is simply the EQ. The Fiio EQ app that comes with the M21 brings this music player to life, having the ability to customize my sound an music on the go is very satisfying. If I prefer more prominent vocals I add more tremble, if I need more bass or less bass I mess with the bass. Now where the magic really shines is with the Stero Expand option. This EQ adds soundstage and insturment separation, which is extremely amazing for Closed Back headphones, like my Sundara closed back. Will this music player make Open Back headphone sound good? Yes! and it can he a hit or miss, very EQ dependant,but I think this music player really shines more with Closed Back, it sound decent with Open Backs. It turns my Sundara closed back into open backs an makes music sound very fun an 3D with pretty good Insturment separation! I have many ifi amps/dacs and all of them have slightly better detail. My Ifi Hip Dac 3 has more detail overall an more textured bass. Though I think the M21 is more superior because they offer a more fun and lively experience that the Ifi Hip Dac 3 cant come close too. If you prefer more separation and a lively sound. With decent detail an looking to make your Closed Back headphones sound godly better then buy the M21. Overall fun factor 10/10! soundstage 10/10! vocal 10/10! bass 7/10! detail 8/10! I am selling my Ifi Hip Dac 3. I hope this review helps!

UPDATE! 12/30/25

there was a recent update to the Fiio m21 software, they added a selection of many audiophile headphones from many brands, so now if you want a sound profile thats more suited for the spefic headphone you are wearing, now you can! I tried the sound profiles for my open backs and they finally gave them a more lively and warm sound that they were missing. I originally stated that the Fiio m21 mainly was Ideal for only closed back headphones, because they didnt really benefit from the previous EQ settings, but the recent update, makes Open Backs sound pretty damn good. I hope they add a option to customize the cassette artwork to our own images. Overall thus music player is a must for Closed Backs, I recommand, and for Open Backs its a decent player, if you dont own one already! I love it!

Screen issue

Love everything about it but i start having issue with the screen about 2 weeks in. I thought my first one was just an issue with my first unit. But after getting another unit. It started happening again. Buy it at your own risk.

Massively recommended

It sounds really well it’s a pocketable useful dap with enough battery life to get me trough a whole day of school and then some the touch screen is responsive and buttons are too the Bluetooth is great perfect dap but I’d suggest power amp as the app instead of the one it comes with

Brian L.

August 29, 2025

Awesome player

I like fiio M21 lives up to what it says the amperage does help driving headphones Grado Bose Marshall Apple wireless all drive the headphones with a lot of kick in volume have not checked out wired headphones yet but I'm sure even better in the sound department. Have tried coax on edifier coax had some clipping problems take the gain down you're okay Bluetooth had no problem whatsoever the biggest thing that stands out with this unit more than others the price for the amperage of the sound you get for the price is worth it separation quality of sound superb case is could be improved too sensitive with the switches but other than that very simplified micro SD card work flawlessly I'm giving it five stars I have took back other dap units didn't live up to the standard this one does this would be recommended for users starting out that one great sound

Small DAP packed with great features and fantastic sound!

Why did you pick this product vs others?:

I own several FiiO products, I'm a FiiO fan.

Sound quality:

Fantastic!

Size:

Convenient.