Review : FiiO K3 – Legacy

Sound performance

For the purpose of this review I used my computer as the main setup, plugged in USB in USB 2.0 mode. 50% Aimp3 with FLAC files, 50% Spotify in high quality streaming.

The headphones ? Onkyo IE-C3 (incredibly sensitive to hiss), Sennheiser HD-800 (magic headphone but a bit tough to drive), Meze Empyrean (for the pleasure) and the Audio-Technica MSR7 (because I like it)

Overall Signature

Good news, the FiiO K3 is a real upgrade from the FiiO E10K. That, of course, is a minimum after four years in the making but it could have been a simple visual revamp. The sound stage is even more precise, gone is the massive yet strange presentation that could occur with the first gen FiiO E10. It’s not as accurate as the FiiO Q5 but there is something much more enjoyable in the sound, a lovely grain that reminds of the IFI iDSD Nano, but better.

The volume knob begins at 9 O’clock and ends at 6 O’clock, but from 9 to 1 the volume is too low to be really usable. I found my sweet spot from 1 to 3 o’clock, after that it gets way too loud for my Onkyo CIEM, even more in Balanced mode.

With all the headphones, except the Onkyo, the FiiO K3 was dead silent. If this is an issue, I’d advise you to stay in single-ended as the balanced output offers more hiss than the others. Once you hear it, it will be inaudible, but better be prepared than sorry.

The bass boost works pretty well, it adds a 6db on the whole bass section from 20Hz to 100Hz. Then there’s a slow roll-off from 100Hz to 2kHz, the rest of the frequency chart remaining untouched. It’s a bit muddy if you rely on it too much, but on thin sounding headphones like the Sennheiser HD800, it’s really interesting. Sure, you could just get a more powerful headphone amplifier, but that’s also more expensive.

Power and drive

Speaking of power, I was afraid the FiiO K3 would not have enough power to correctly drive a good pair of headphones. Strangely… it worked well, even with planar headphones like the Empyrean or my old Audeze EL-8C.

You need to put the K3 in high gain and turn the volume up to 70%, but it works ! There was no distortion whatsoever and the sound is still loud enough to enjoy your music with a small setup. Don’t get me wrong there, it’s not magical and you can clearly hear some limitations with high-end gear.

Keep it to sensible headphones like the Audio-Technica MSR7B or even more the Meze 99 Classics and you get a terrific system for a very affordable price. This could even become your main setup at the office, like for me.


Thanks to the new ADC volume control, there is no imbalance even at low volumes, this is rare enough to be noticed. This is true in both single-ended and balanced mode, so you do not have to worry.

The sound is even on the whole frequency chart, if you don’t activate the bass-boost you could say it’s almost transparent. Still, you can hear a very slight bump around 5kHz, this puts a little emphasis on voices. In single-ended mode you don’t hear it as much as in balanced mode though.

Bass : tighter than you would expect, it doesn’t slam as hard as the FiiO Q5 but that was easily fixed with a bigger amp connected to the line-out. If you like big-heavy bass, the bass-boost gives you quite enough of it. You lose in definition and this feels like the Cmoy BB : addictive but deceptive on a long run. I extensively listened to Solee with the FiiO K3, on some DACs it can really become painful but not on this one. It’s a good balance of fun and performance.

Treble : the little voice emphasis is pretty interesting with jazz and pop. You can definitely feel the parenthood between the latest FiiO generation : a mellow, soft treble, the velvet signature of AKM chips. Where Sabre DACs amazed me with technicalities, AKM seems to be kinder to the ear. If you love Diana Krall or Gregory Porter, you’ll be fond of the FiiO K3.

Highs : a bit recessed in my opinion, even in balanced mode the Fiio K3 doesn’t reach as far as others. Like the bass, once you plug a good amp to the line-out you can hear what’s missing. Surprisingly it was when I connected the FiiO K3 to my new KEF LSX speakers that I could truly hear what this unit was about. It’s much more potent that I expected, with good extension and quick attack/delay. Violin sound is a good way to fault a unit and this one did a pretty good job on most of my classical playlist.


Let’s cut to the chase, I wanted the FiiO K3 to be good… and it is. It’s so versatile, allowing you to plug almost anything to it on your desktop. It’s powerful enough to drive classic headphones and if you plug another amp to the line-out, it’s just brilliant. It’s a carefully designed product which had to be at least as good as its previous iteration, but the K3 is better in every way.

Honestly, the full late-2018 line-up from FiiO has killer products. They are well made, cheap and cover basically every need. Even more, they all sound good and even great like this little FiiO K3. It’s a bit late now for a christmas present, but in 2019, threat yourself with one of these… You won’t regret it, period.


A nerdy guy with a passion for audio and gadgets, he likes to combine his DAC and his swiss knife. Even after more than 10 years of experience, Nanotechnos still collects all gear he gets, even his first MPMAN MP3 player. He likes spreadsheets, technical specs and all this amazing(ly boring) numbers. But most of all, he loves music: electro, classical, dubstep, Debussy : the daily playlist.


  • Reply December 20, 2018

    Loganaden Balakrishna VEERAPEN

    Big thanks Nanotechnos for this excellent review. Lately I’ve been on the fence to replace my trusty Fiio E10 (which I use with my android phone) with either the K3 or Q1 MkII (only power output and sound quality are my criteria). I know its Berkhan who reviewed the Q1 MkII, however I would very much appreciate if you give a brief comparison to the K3.

    • Reply December 31, 2018


      Personnaly, I’d go for the K3 if it’s for a desktop use. The Q1 is very nice, but I think the K3 outperforms it, especially with its better soundstage 😉

  • Reply December 20, 2018


    i’ve got an fiio a3 that i pair with my v-moda crossfades & i use them for absolutely everything; music, games, movies, etc.

    i realize both are somewhat outdated but the two work phenomenally together and i don’t see an immediately obvious reason to upgrade!

    best qualities are definitely sound stage and lower frequencies, which i’m big on a lot of bass and surround.

  • Reply December 20, 2018

    Sæmundur Eric

    Hi, how would you chose Q5 or K3 from Fiio ?

    • Reply December 31, 2018


      The Q5 is better overall, but it’s also more expensive and bulkier

      • Reply March 3, 2019

        Im a newbie

        Hello, nice review ma frend.
        But, im curious how the k3 compared to ifi nano bl?

  • Reply December 28, 2018


    does K3 wil be good pair for fiio fh1? im planning to get them both , does the K3 do the “Pooping” sound when plugging an iem to it? i have fiio e10k it does produce “poop”sound when i plugging my iem even in zero potensio ( idk what caused this and im afraid it will harm to my iem)

    • Reply December 31, 2018


      Fortunately I didn’t hear any pooping (like the word) with the K3. I think they used a better filter to avoid feedback like this. 🙂

  • Reply December 28, 2018


    I want to use a Headphone Dac/amplifier for my laptop just to improve the sound when listening to YouTube etc. What would be better the Fiio K3 or the Schitt Fulla2 if I was to use Beyerdynamics T990 headphones?

    • Reply December 31, 2018


      The Schiit should have more power to drive your Beyerdynamic.Also, it will sound a bit more metallic, the highs are a bit too proeminent for my ears. Both are solid performers, take the Schitt if the Beyer is you main headphone, the FiiO for everything else.

    • Reply April 24, 2019

      Maksym Nits

      With such a nice setup you’re planning to have, listening to music from YT is a sound quality killer. Download only in CD-quality, like .flac, .aac, an so on. Forget about mp3 and YouTube, respect your ears and the gear you own that companies tried to make perfect for so long!

  • Reply January 9, 2019



    I’m looking for a DAC/AMP for my pc to drive my new Hifiman HE4XX headphones. This will be my first DAC/AMP btw.

    Do you think this will be sufficient or should I shoot for something better?

    I’m guessing the K3 can be connected to an iphone but that would drain the battery, am I correct?

    Thank you, nice review!

  • Reply January 15, 2019

    Alex Di Lolli

    Great review, did you had the chance to compare it to the iFi nano iDSD BL?

  • Reply February 17, 2019


    Hi, nanotechnos, does K3 can drive hd800 without any problem at all? in SE and balance? Thanks

    • Reply February 17, 2019


      No it’s not build for that really

  • Reply April 6, 2019


    great review, thank you! I’m interested in using this device to improve the sound quality of my laptop setup. I have a macbook pro into which I’m plugging JBL LSR305 studio monitors. Would plugging the speakers into this unit and then the K3 into my macbook pro be an effective solution for improving audio quality? I’m primarily streaming Qobuz using the Audirvana app integration.

  • Reply February 24, 2020


    i want to buy and use it for hd58x jubilee , its good for this can ?
    i should decide between k3 , e10k and dragonfly black ? which one do you suggest ?

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