A couple of weeks ago, I shared that I broke up with Spotify. I have tried the service at times again, mostly on Fridays to see what was in my Release Radar playlist, but I still kept finding the occasional fake-AI song.
But I didn’t stop listening to music. In fact, I don’t think I’ve ever listened to as much music, be it older songs or stuff I didn’t yet know.
All this is due to a new device I’ve purchased, the FiiO M21 DAP (digital audio player). Since owning the FiiO (and two pairs of IEMs, more about them in a second), I’ve discovered new artists, changed the way I listened to music, subscribed to two new streaming services, and even have a new favourite band.
The hardware
But first, let’s talk about the hardware.
Inside the box you get the basics: a USB-A-to-C cable, the player, and a slim gray silicone case. The case looks great and matches the titanium-bronze rails, but the bottom edge never really grips the frame and the raised button covers make the playback controls hyper sensitive, so I ended up skipping tracks by accident. I still slip it on when I throw the M21 in a bag, yet most days the player runs naked because that frosted glass back and the bronze highlights are too good to hide. It is simply a beautiful device.
The FiiO is an Android-based DAP. Think of a new iPod, with better audio components, a touchscreen, and access to the Google Play Store. FiiO has several different DAPs and there are other brands like HiBy, iBasso or Shanling. (The community calls these products “Chi-Fi” for Chinese Hi-Fi.)
The M21 is somewhere in the lower middle end. But having used this for a few months, and still believing I’m far from being an audiophile, I don’t know if you’d need anything more expensive. (I honestly think the cheaper JM21 might also just be good enough for 99% of people, but this is overkill.wtf, not reasonable.wtf.)
The M21 is a chonker. Compared to an iPhone 16 Pro, it has a significantly smaller screen but is about twice as thick. At first, I was surprised by its thickness, but after using this for like a day, I came to appreciate the heft.
And compared to an iPhone, the FiiO has way more buttons. Besides the typical volume rocker and power button, you’ll also find a play button, a forward and a backward button respectively, and a sort of action button that you can map to certain features that I have set to tape mode for the lack of better ideas.
There are also two toggles, one locks the touchscreen and buttons so you don’t trigger it in your pocket, while the other enables D-Mode, which stands for desktop. The idea here is that you can connect the FiiO by cable to a computer, and with this toggled, it bypasses charging and instead powers the device directly. I’ll explain this in more detail in the software section.
That action button is more of a FiiO Music shortcut than a true system key. Most of the presets only work with the stock app, so I tried a few options and left it alone again. The hold and D-Mode toggles sit under the volume rocker, which is handy, but they flip in opposite directions so I still flick the wrong one when I am half asleep. Also, D-Mode has to be off if you want the battery to charge. I forgot that once, went to bed with the switch up, and woke up to a dead player. Lesson learned.
FiiO also sells a plastic cassette shell for somewhere between fifty and ninety bucks. You slide the M21 into it, tape mode kicks on, and the UI turns into a spinning cassette. It is completely unnecessary, blocks the hold switch, and remaps the buttons so volume up sits where play used to be. But the animation is charming and you can enable the same tape mode in software without the shell, so every once in a while I still toggle it just because it looks cool.
It might sound weird, but that denseness and the aluminium + glass-back body make this device feel substantial and high-quality. It simply feels good in hand, and not too heavy at 193g.
The 64 GB of built-in storage fills up fast once you start caching lossless albums, so I threw in a 512 GB SanDisk microSD. Between the card and the internal space I am already using about 100 GB, and that is with just a dozen albums downloaded in Apple Music, Plexamp, and Qobuz. Lossless files are huge, so having that card slot is non-negotiable.
Spec-wise, the easiest thing is to share this list:
- OS: Android 13
- Processor: Qualcomm Snapdragon 680
- RAM: 4 GB
- Storage: 64 GB (expandable via microSD up to 2 TB)
- Display: 4.7″ (750×1334)
- Battery: 4000 mAh (≈15 h SE / 12.5 h balanced)
- DAC: 4× Cirrus Logic CS43198
- Outputs: 3.5 mm SE / 4.4 mm balanced / SPDIF
- Bluetooth 5.0 (SBC, AAC, aptX, aptX HD, LDAC, LHDC)
- WiFi: 2.4/5 GHz dual-band
- USB-C: dual ports (data/power and dedicated input)
- Charging: USB-PD 2.0 / 3.0 fast charge
- Weight: ≈193 g
Let me explain some of the items on this list:
While the Snapdragon 680 is, at this point, ancient and far from smartphone level, it’s still significantly faster than the chip used in much more expensive DAPs. And while 4GB of memory is low, it’s more than enough to listen to music. (Apparently, the Chi-Fi DAP market uses older chips since they are more mature than cutting-edge stuff.)
In practice the Snapdragon 680 feels totally fine. Spotify cold-starts in about three seconds, Qobuz takes four, and scrolling big album grids is smooth as long as nothing else is updating in the background. It is still a beat slower than my phone, though.
Then there’s the DAC (Digital-to-Analog Converter) setup. That’s the part converting digital bits into sound you can hear. The M21 uses four Cirrus Logic CS43198 chips, two for each channel. That means cleaner conversion, less noise, and better stereo separation. It’s basically the reason your music sounds more detailed and alive than on your phone.
As for the ports:
- 3.5 mm is the classic headphone jack. It’s what I use 100% of the time.
- 4.4 mm is the balanced one, giving more power and less interference. Although some audiophile-people think that this port is basically just hype, and I personally used it once to test and saw no difference.
Underneath you get two USB-C ports. The left one handles data, file transfers, and USB DAC duties when you hook it to a computer. The right port is outlined in red and is the one that handles power: desktop mode, fast charging, and the secret super high gain setting that only appears when a high speed charger is plugged in there. All the headphone jacks live up top, which still trips me up. I have owned the M21 for weeks and I still grab it upside down at least once a day. When it sits on a desk the cables stick out of the top like antennae, so I often angle it sideways just to keep things tidy.
For local files I rarely plug the player into a computer. Plexamp handles everything: I mark an album as “download” on the M21, it pulls the lossless files from my Plex server over Wi-Fi, and stores them directly on the SD card. If you prefer drag-and-drop you can still mount both drives over USB, but living inside Plexamp means I never have to touch a cable.
Power output was something I had to look up. Single-ended pumps out 290 mW at 32 ohms, or 480 mW if you engage that super high gain charger trick. Balanced jumps to 720 mW and 950 mW respectively, which sounds impressive even if I do not own anything that needs it.
You also get 120 steps of volume on each gain mode and FiiO claims the single-ended output impedance stays under one ohm, so sensitive IEMs behave nicely. All of this is very nerdy and I barely understand any of it, but I appreciate that the headroom exists even if I mostly live on low gain at around 70 volume ticks.
But let’s talk about two things that I still struggle with mentally, although they don’t really make a big difference in day-to-day usage: Android 13 and the 4000 mAh battery.
Android 13 is old! It came out over 3 years ago. And while it’s still a stable, and supported platform, my biggest fear is that over time the apps I rely on (more about them soon) will just become unsupported. So far everything I throw at it works out of the box and both Qobuz and Apple Music support Android versions far older (5 and 6, if I remember correctly). So this might not actually be a problem, it’s just a me-thing.
What is, however, a problem is battery life. It’s just not that good, it’s only decent. While I don’t have to charge this as often as my phone (daily), I am close to charging the FiiO every second. And somehow I find this too much for a music device. I remember the good old MP3 player days that you basically only charged once a week. But I guess that’s the disadvantage of using something based on Android.
FiiO rates the battery for about 15 hours on the 3.5 port and 12 on the balanced side. That seems optimistic. With Wi-Fi on and a mix of Apple Music offline files, I see maybe ten to eleven hours total use, which translates to charging every other evening. The M21 also kills Wi-Fi in standby to save power. That helps sleep drain a lot, but it also means I sometimes pick it up, hit play, and realize that the albums I saved to Qobuz don’t appear immediately on the FiiO. At this point it is just part of the routine: flip it on, wait a few seconds for Wi-Fi to return, and plug it in every second night.
But let’s talk about Android.
The Software
Running Android might be a disadvantage battery-wise, but software-wise it’s the reason I picked this in the first place. I can just install whatever streaming service or music player I want to.
And for a while, I ran multiple. The list is as follows:
- Spotify: I don’t use this anymore, but still pay a sub for my family. I check this from time to time just to see if some artist released something new.
- Apple Music: This is the service I probably use the most. I have a bunch of playlists I moved over via Music Transfer, and I listen to them here. Music here can be lossless.
- Qobuz: Qobuz is the service I want to use the most, but decided to use it primarily to listen to full albums. They are known for lossless music, and I even bought albums here.
- Plexamp: And this is where that bought music lives. I run Plex for, ehm, my Linux ISOs, and also added my music collection to this.
- Pano Scrobbler: This app scrobbles every music played to my Last.FM profile (as Apple Music, for example, doesn’t support native scrobbling).
- Classical: This is Apple’s Classical music app. I like listening to video game and film scores while writing or reading, so this is what this app is for.
- Pocket Casts: A podcast player I haven’t yet used on the FiiO.
- Roon & Roon Arc: I used this service for a while, and while I tremendously enjoyed it, I couldn’t convince myself that paying monthly to play local files is a good choice.
- Niagara Launcher: I use this on every Android device ever.
- Equalizer: I will explain this in a second, but the FiiO has a built-in equalizer that adopts parametric EQ to all output, no matter the app.
Because this is Android, I can skin it however I want. Niagara Launcher trims the home screen down to a single list, so I only see the apps I care about. Also, I hide everything else behind app pinning. Swipe up to pin Plexamp or Qobuz, hand the player to someone, and it behaves like a dumb MP3 player until I enter my PIN again. I still have the full Google Play Store when I need to install something new, but most of the time the UI is as minimal as a classic iPod.
The built-in EQ sits right in quick settings, so you can toggle it without diving into menus. By default it opens a familiar 10-band graphic view. Hit the Advanced button and it turns into a full parametric editor where you can set exact frequencies, change Q (basically the width of the adjustment), or turn a band into a shelf. There is even a little effects pane that boosts bass, treble, or width for people who do not want to mess with individual bands. The only bummer is that the headroom slider is manual and there is no way to import TXT profiles, so if you download a Squiglink preset (more about them below) you still have to type every value in by hand. (Which is what I did.)
When I work at my desk, I flip D-Mode on, plug the red USB port into a charger, and run the data port to my Mac. The M21 shows up as a USB DAC instantly and the battery stays out of the loop, so I can listen all day without cooking it. You can still toggle between low, medium, high, or super high gain in that mode, and the tape UI works there too if you want vibes over practicality. It is overkill, but that is kind of the point.
The Music Experience
But how did the FiiO change the way I listen to music? Basically, I need to divide this section into two parts, hardware and software/services.
Hardware
I use the M21 in combination with one of my two pairs of IEMs: the Moondrop Aria 2, and the Pula Unicrom. Both are probably the best sounding audio devices I’ve ever had the pleasure of putting into my ears. Coming from AirPods Pro (Gen 1) the difference is noticeable. And remember, I am not an audiophile, so there is probably stuff I can’t even hear, but I can hear a difference compared to the AirPods.
A side-note on the IEMs: I have two pairs, because HiFiGo, where I bought all this stuff, sent the Pula Unicrom for review.
The Pula Unicrom costs $79 (or $69 if you caught the early-bird window) and runs a single 10 mm beryllium-plated dynamic driver inside a resin shell (I looked this up, I have no clue what it means). The faceplates are stabilized wood and look more expensive than the price suggests (this I can comment on). The shells are on the smaller side, which should mean an easy fit, except the nozzle is too long for my ears. The stock cable is a soft braided modular one that swaps between 3.5 and 4.4 mm plugs, but the memory wire sits a little awkwardly, so it never feels quite as natural as the Aria cable when it loops behind my ear.
Now, this nozzle and cable thing seems to be a me-problem. I looked up other reviews, and while they hurt my ears, nobody else complained of fit. Which is a bit of a problem with human anatomy and everything you stick in your ears. Since we’re all unique, what others might fit, might not fit you. And unfortunately, the Pulas don’t fit me.
The Aria 2 go in a different direction: fully metal shells, a faceplate inlay, and another modular cable option that feels nicer over my ears than the Unicrom’s wire. They still feel like little tanks next to most resin shells.
I struggle to qualify how the Aria 2s and Unicroms sound, but let me try:
Tonally the Unicrom leans hard into mid-bass warmth. There is enough sub-bass rumble to feel kick drums, but the emphasis sits around the mid-bass, so you get extra thump. The upper mids carry plenty of vocal energy without turning shouty. These sound, what the community calls, “fun”. I think these are great for gaming.
As for the Aria 2, sound-wise they are smoother, a touch more balanced, and only lightly V-shaped. Bass is controlled, mids sit forward enough that vocals feel present, and the treble stays polite while adding enough sparkle so things do not turn dull. I can wear them all afternoon without fatigue.
The audiophile community has this whole way of measuring the output sound of headphones with the goal to have a comparable metric. It’s called a frequency response curve and basically shows what the bass, mids and highs/treble look like on a graph.
This is the curve for the Aria 2:
And this is the curve for the Unicroms, both measured by Super* Review (the YouTuber I linked below):
And here in comparison:
Let me try to explain what you see. Since the line in the lower frequencies is higher for the Unicroms, it means bass is more pronounced than on the Aria 2s, while the treble on the 2s is higher, as per that squiggly line in the higher frequencies.
What this means is that the Pula IEMs are more bass-heavy, while the Aria 2s sound brighter. Those curves also match what I hear: the Unicrom bass shelf lives around 100 Hz, which lines up with that big hump on the chart, and the Aria 2 spike around 3 to 4 kHz explains why vocals pop a little more. Seeing the measurements next to each other helped me understand why EQ bands changes the character so much.
I propose you watch this video to exactly learn how to read a frequency response curve.
Now, one more thing you need to learn about that curve: There is a thing called a meta, or a target curve. What this means is that this is a curve on that graph that is deemed the most pleasing sound profile for the average user.
(Now, the target curve might not apply to you: the anatomy of the ear plays a huge role in how music sounds, so what sounds good to others, might not sound good to you. Same as for fit.)
That’s where a parametric EQ comes in, because no matter the device you use, as long as you don’t go ham, you can make target every other curve.
Here is one more video to explain that:
So that Equalizer app I mentioned above is what you’d use to make this happen. I used it to bring the Aria 2 closer to the Harman Target Curve, and thus making it a bit more V-shaped (like the Unicroms), so a bit bassier. The idea is that over time you learn how you like your music and you’d build your own parametric EQ, but ain’t nobody got time for that, and my music sounds good enough anyway.
Software
Above, I shared what services and apps I use on the FiiO, but I need to share a few more thoughts on software experience.
Since going away from Spotify, I basically switched from listening to playlists to primarily listen to full albums. And I do listen much more focused to my music, actually sitting down with the IEMs on my couch, and at times Genius to read the lyrics.
I am jumping between Apple Music and Qobuz to do this, and both services are honestly interchangeable.
Both have lossless music, both have a large library (although Qobuz lacked one album I was looking for, but you can report that), and both have good enough apps. In the end, it all comes down to what recommendations you prefer, and Apple Music is more playlist-based, while Qobuz recommends more albums. I prefer how Qobuz handles things.
And if you want to try Qobuz, here are two months for free:
When there is an album I particularly like, I decide to buy it, and add it to Plexamp. So far, I’ve got 12 albums like that.
Jumping between services is easy, thanks to TuneMyMusic, which allows me to sync music between services for as long as I pay a subscription. (Which I stopped doing this month.)
Music Discovery
Since I try not to rely on algorithms too much to discover new music, I had to change how I found new stuff.
There are basically now three and a half ways:
- I subscribed to this newsletter, that sends out a new recommendation every week. Gabby has impeccable taste, so I can recommend this newsletter wholeheartedly.
- I often check on Bandcamp and Qobuz whatever their respective editorial teams recommend, and found some new indie bands this way.
- I ask friends for recommendations.
(3 and a half. I at times still check what Spotify tells me, but this is becoming rarer and rarer.)
I’m also guessing that the more I scrobble to Last.FM, the better their recommendations will become, but that might just mean that I’d rely on an algorithm again.
To be fair, this experience is probably convoluted and too overkill for most people. Most people don’t need a separate device to listen to music, they don’t need to jump between multiple services to discover new songs, and I believe the majority of people don’t need to even know what a frequency response curve actually is.
But I believe everyone should at least once try good sounding IEMs, try to gain back control of their music discovery, and I strongly believe that replacing a smartphone with a dedicated device is the more mindful way to go.
The FiiO M21, the two pairs of IEMs and the different services and tools I use allowed me to experience music in completely new ways, and I’m planning to just go deeper into this rabbit hole.