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FiiO K3 Headphone Amplifier & USB-C DAC Review

  1. Wyville
    FiiO K3 USB DAC/Amp - Easy Peasy
    Written by Wyville
    Published Jan 31, 2019
    Pros - Intuitive to use, significant improvement in sound quality over the internal sound of a MacBook Pro, excellent build quality, great value
    Cons - Some sync issues (with older MacBook), slight noise with sensitive IEMs from the 2.5mm balanced out
    FiiO K3

    I would like to thank FiiO for providing me with the K3 USB DAC/Amp in exchange for my honest opinion. No incentive was given for a favourable review.

    FiiO K3 (at a glance)
    • USB-C DAC and headphone amplifier
    • Decoding up to 384kHz/32 bit PCM and native DSD256
    • DAC: AKM AK4452
    • Op amp: 2 x OPA926
    • Low-pass filter: TI OPA1612
    • USB chip: XMOS XUF208
    • USB Audio Class 1.0 and 2.0
    • 3.5mm SE and 2.5mm balanced headphone out
    • 3.5mm line out
    • Coaxial out
    • Optical out
    • ADC volume control
    • Gain and bass switches
    • Output 3.5mm: 220mW(16Ω, high gain)/120mW(32Ω, low gain)
    • Output 2.5mm: 320mW(16Ω, high gain)/200mW(32Ω, low gain)
    • Price: US$109.99


    FiiO is a very well established name among audiophiles the world over. The Chinese company was established in 2007 and has built up a reputation for affordable products with a high value ratio. You pay a budget price and get high quality equipment in return, which I think is why so many audiophiles have cut their teeth on FiiO equipment when they started out in the hobby, with DAPs such as the venerable X1, X3 and X5. By now FiiO has expanded to include higher end products as well, such as the X7 mkII DAP. They also expanded into IEMs where FiiO again look to set the value bar increasingly high, most recently with the release of the FA7 IEMs, where FiiO have made optimal use of 3D printing technology for mass production. This technology can help push down the price and maintain a consistent quality in large batches, as well as some of the other advantages 3D printing brings (e.g. allowing more intricate designs).

    For me it was apparently only a matter of time before I too gravitated towards FiiO. The audiophile bug has well and truly bitten me and I spend a lot of time listening to music, reviewing gear and generally just have something stuck in my ears all day long, be it IEMs or earbuds. The main downside of that, I discovered, is having a DAP (my AK70) with only an 8-10 hour battery life that is impossible to use when charging because of the noise that creates. It could theoretically be used as a USB DAC, but there too I found things to be far from optimal. Since I do a lot of listening behind my desk, I started wondering about a desktop solution. Being an audiophile that quickly escalated into plans for silly expensive equipment I did not have the money, getting that all too familiar look from the missus and seeing her hand slowly reaching for the frying pan.

    So in the interest of self-preservation, I felt it was high time to be sensible and consider an option that would make for a good introduction into desktop gear without breaking the bank. That is also the way I will approach this review. I am very much a music lover and don't generally delve into the technical aspects of the gear, so I am not going to be the right person to compare technical specs. My aim here is to write for those who, like me, want to upgrade their desktop specs in a simple and affordable way. That is what attracted me to the K3. From what I saw the K3 is a tiny and elegant solution that offers FiiO's trademark high value ratio and is intuitive to use. If that does not sound attractive to the desktop solution initiate, I don't know what does. So let's see how it all worked out in practice.

    The packaging of the FiiO K3 is very much a 'no nonsense' affair. It comes in a white box that keeps the DAC/Amp securely in place and added are only the bare essentials such as the data cable, 2 sets of anti-slip pads (only one set pictured, as I had the other set already installed on the K3), a quick start guide and warranty card. Simple, effective and you really don't need all the fluff, especially at this price point.



    Build quality
    The first thing I noticed when I took the K3 out of its box was how solidly it was built. It is a small and light device, but the black CNC'ed aluminium body feels very solid in the hand, not fragile or cheap at all. It looks really quite elegant and I like it sitting next to my MacBook Pro. The switches are quite small, yet easy to reach even with earphones plugged in and they have a nice light 'click' to them when switching, so it does not require a lot of force, nor is it easy to accidentally switch them. The volume wheel that also acts as the 'on/off' switch feels very nice. There is a healthy bit of resistance and a lot of smoothness that helps to make precise volume adjustments easy, even with sensitive IEMs, and avoids accidentally changing the volume if you brush against it. The body is a little light relative to the resistance in the volume wheel, which is placed quite far to one side (right), so with one-finger operation you might end up flipping the K3 rather than turning the volume up (no such issue turning down the volume). When I operate it, I usually just use my thumb on the other side (left) for stability, which I do intuitively anyway and then one finger can easily switch the K3 on and control the volume very precisely.

    On the front we find (from left to right) a 2.5mm balanced out, 3.5mm Single Ended out, bass switch, gain switch and volume wheel. The switches are simple with only two options, low gain or high gain and bass boost on or off. Around the volume wheel is an RGB light indicator that changes colour depending on the sampling rate. Blue light for 44.1 or 48kHz, yellow to indicate above 48kHz and green for DSD. Once I also got a red light, which I suspect was just the K3 telling me I was being an idiot for plugging it into my PS4 (more on that later).


    On the back we find (from left to right) a 3.5mm line out, USB type C port, Coax out and optical out. Above the USB type C port is also a USB mode switch that allows the user to choose either USB Audio Class 1.0 or USB Audio Class 2.0. The difference between the two is that USB Audio Class 1.0 is limited to files up to 24- bit and 96kHz, whereas 2.0 will go up to DSD256 and 384kHz. For Mac OS users it is easy, as Mac supports 2.0 without the need for installing any additional drivers, while Windows users will need to install those. They can be downloaded freely from FiiO's support page: https://fiio.com/supports


    Basically it is as simple as plug-and-play. On my MacBook I did need to go into the System Preferences and indicate in the Sound menu that I wanted my sound through the K3, but that was nothing more than a button click and my Mac instantly recognised the K3.


    The supplied cable is a nice length so that you can move the K3 around your desk and if you have some OCD tendencies like me, loop the cable around the monitor neatly so it is as much out of view as possible. It is also not too long either so that there is no risk of a complete and utter mess of tangled up cables running across the desk somewhere. My OCD thanks you FiiO.

    Once connected there is the choice of 2.5mm balanced or the standard 3.5mm headphone out. I love this option, as most of my cables are terminated in 2.5mm and while I do have adapters, I prefer not to use those. FiiO indicates that the balanced out gets a power boost of around 50%, which might explain why I got a tiny bit of hiss from the balanced out when using my most sensitive IEMs, the Empire Ears Phantom. Mind you, the noise floor is extremely low on the K3 and my Phantom are the only IEMs I have where I can hear a faint hiss. As soon as the music starts to play there is nothing really to notice and switching from balanced to the 3.5mm single ended out also reduces the noise to imperceptible levels. I can't stand hiss, as I find it far too distracting, but have happily used my Phantom from the balanced out. I think that indicates clearly that it is a really very minor issue and some people might not notice it at all.

    Generally speaking the K3 has worked flawlessly. It is very intuitive to connect and there is very little that can go wrong. I have had two issues though. The first was that at one point after having used the K3 for a quite a while and turning the K3 off, my MacBook lost all sound and required a restart for it to come back. I have had similar issues in the past, so it was unlikely a direct cause of the K3 and I have not had it since either. The second issue was that when using the K3 to watch videos on YouTube, the sound sometimes got desynced and the pictures would lag behind the sound. Pausing the video and restarting it got a fast-forward of the images to catch up with the sound again. I find this issue a little baffling, as I could imagine the sound to lag behind a bit (I had that while using the AK70 as a USB DAC) but not the other way around. I have not encountered it without using the K3. With music something similar seemed to happen, like the music was out of sync with itself and had to recompose briefly.

    Arguably the most important bit and one where I have to look at things a little differently from what I usually do. Usually I analyse the sound with the familiar sections such as "bass", "mids" and "treble", but I agree with those who point out that this does not make sense with a DAC/Amp. Only the bass boost does something to the sound, while without it the K3 is ruler flat. That is also something I really like about the K3, that it turns my MacBook into a neutral source, while my AK70 is more warm-natural sounding. The two compliment each other really well.


    The K3 does an excellent job to scale the sound of my Mac. Without it the sound is tinny, thin and quite harsh with all of my IEMs and earbuds. I regularly use my Lyra Collection earbuds for watching YouTube and vocals sound nowhere near what I know the earbuds are capable of. It is always a bit harsh and what is worse is that the volume control on my Mac is horrific, always requiring me to fine tune with the slider in YouTube because the main volume is at its lowest setting. With the K3 the sound matures and notes sound fuller, vocals sound smoother and everything gets more space to breath. There is also much more precise control over the volume level, as the K3's volume wheel is a world apart from what I can do on my Mac.


    When I want to listen to music, my Mac is not really an option. My Phantom sound like the snowing of a TV set and using less sensitive IEMs such as the Dita Fealty is not helping there either because they end up sounding surprisingly harsh. Moving one step up to the 3.5mm single ended out of the K3 is a significant step up. The sound is clean, even with my Phantom, notes sound fuller, the image is more stable, the stage is larger and everything is just really nice crisp and clear. Switching to the 2.5mm balanced out is another step up, although not quite so significant this time. My Phantom get some hiss, but not annoyingly so, and otherwise it is much the same in terms of improvements. Notes sound a bit fuller still, a slightly larger and deeper stage and the image again feels a little more stable. Especially with the Fealty I also noticed that everything started to sound smoother and more refined. Because these are harder to drive dynamic driver IEMs, I thought I would try those on high gain as well, just to see if it made any difference at all and I sensed some added depth to the image and a slight further improvement to the overall smoothness.

    Of course I felt I needed to see how well the K3 stacked up against my (much more expensive) AK70 DAP. Apart from a difference in tone, which is warmer and smoother, the AK70 creates a much more holographic stage with the Phantom and can push the stage of the Fealty even further, especially in terms of depth. The background of the AK70 is absolutely pitch black and more micro details come through, something I notice especially in the texture of violin strings. Even so, the K3 stacks up surprisingly well and I have had no reservation about using it for my reviews. In fact, the neutral tonality is very helpful, as especially the balanced out of my AK70 seems to have a very laid-back treble that has caused some synergy issues in the past where I ended up switching to the SE out. With the K3 there are no such issues, as it is neutral and the SE and balanced out are the same in terms of tonality.

    As I indicated, warmth and impact can be added through the bass switch. To be honest, I only used it once to have a bit of fun, as I found the sound quality of the K3 to be great without adding in the bass. It can be a lot of fun and I can see sense in it if you are watching movies or playing games and want to add some thump to the sound. Speaking of gaming, I did look into the possibility of using the K3 with my PS4 because I would have liked the bass switch for that, but the optical out is... well... and optical "out", not "in". So in my understanding the K3 can transfer a digital signal from a USB source, out of its optical out and into a different DAC (a non-USB DAC), but it cannot receive a digital signal optically. That was a little disappointing, although admittedly it would have only been a fun little extra and not what I was looking for in the K3 in the first place. I guess it is a sign that I should not have given up PC gaming in favour of becoming one of the lowly "console peasants".

    So did the FiiO K3 live up to expectations? Does it offer that high value ratio that FiiO is so well known for? The answer is a resounding 'yes' to both questions. The FiiO K3 is a great performer in a tiny and elegant package that is intuitive to use and has a very palatable price tag (no risk of 'close encounters of the frying pan kind' here). I had some minor issues with desyncing that I suspect have more to do with my Mac's software than the K3 itself, but even so it has been a joy to use and will certainly see continued regular use. I think it is a great solution for anyone looking to upgrade the sound of their computer (Mac or Windows) without the need for opening it up or loosing too much space on their desk. Or indeed, those looking for a solution they can easily take into work and install without having to explain to the boss why you consider "their computer" inadequate for your audiophile needs. Great job FiiO!
      FiiO likes this.
  2. AvijitSingh
    A Wonderful Product
    Written by AvijitSingh
    Published Jan 25, 2019
    Pros - Price, Type-C, Clean Sound, Plug and Play.
    Cons - Included Cable, No Optical Input.
    Hey everyone,

    Today I will be reviewing the Fiio K3, a new portable DAC&Amp by Fiio. This unit was kindly provided by Fiio for review and I would like to thank Lily, over at Fiio, for this opportunity. SO with that being said, take anything I say with a grain of salt. And if you have a chance, give this unit a try yourself and form your own opinion.

    For the purpose of this review, I compared the K3 to two different portable/Transportable Amp and Dac Combinations – the IFI Micro IDSD BL ($599USD) and the IFI Nano IDSD ($199 USD) – as they were what I had access to at the time of doing the review. I also compared the K3 along with the onboard of my MacBook Pro 2015. The In-Ear Monitors I used were primarily the Campfire Orion, the Oriveti New Primacy and Ear Sonics Velvet V2, just to see how the K3 performed? with different In Ear Monitors . I did my best to match the volume of each product and, since the IFI products did not have a 2.5mm output, the 3.5 was used on all three when doing the comparisons.

    The Songs I Listened to Were:

    · Shiver by Lucy Rose

    · On & On by Joey BadA$$

    · Righteous Minds by Joey BadA$$

    · Time Lapse by Ludovico Einauldi

    · Labyrinth by Mondo Grosso

    · For Now I am Winter by Olafur Arnalds

    · Visions by Vanilla

    · Ambitionz az a Ridah by Tupac

    · Thriller by Michael Jackson

    · Second Hand News by FleetWood Mac

    These songs were 320kps, Flac, and the last 2 DSD files just to cover all of my bases. It is important to note that the zx300 does not fully convert DSD unless you are using the balanced output.

    Unboxing, Packaging, and Build


    The K3 is a very affordable unit with a price tag of $110 USD or $160 CAD, and with such a low price point the packaging is incredibly simple. In the box you will find three things: the User Manual, the K3, and a Type C cable. The build and finish on the K3 are fantastic as it is made up of metal, and has nice soft rounded edges. The digital volume nob is very smooth with a good tactile feel, especially with the knurled finish. Overall the build quality is great. The only issue I had here was not with the unit itself, but the cable that was included in the packaging. In my case, if the cable was touched when the unit was operational and receiving data from the source, it would just stop working all together. It seemed like something had disrupted the signal and I would have to disconnect the cable, turn the unit off and reconnect everything. This issue was resolved by using a different cable – such as a Aukey Type C – and I had no more issues of this type.

    Sound and Comparisons


    Getting into the most important aspect of this review: how the K3 sounds. I personally find it very difficult to just mention how something sounds without having something to compare it against, but I will try and describe how the K3 sounds as best I can.


    The K3 is a very clean sounding device. It provides little to no background noise or hiss. There is a noticeable increase in detail and separation, as well as a touch of warmth with a slight improvement in bass impact; nothing harsh or off putting about the sound. When you switch to the balanced output, I found all of this to be further improved upon such as separation, imaging and more power along with with a touch more forwardness to vocals and a slight widening to the already very good soundstage. At this price, there is very little I could ask more for.

    K3 vs IFI Nano IDSD BL ($110 USD vs. $199 USD)

    The most immediately noticeable thing when I was listening to Thriller by Michael Jackson was that the K3 had a noticeable larger soundstage, while in terms with depth, they were about the same. Vocals on the K3 seemed to be a touch pushed back when listening to something like Shiver by Lucy Rose. Cymbals and strings were a bit more prominent on the K3 due to it having a slightly brighter sound than the Nano. Additionally, the bass boost option is a nice touch that the K3 has over the Nano, but the Nano does bass better than the K3 with slightly better impact and decay. While in comparison the K3 with bass boost on was slightly less controlled, this was especially noticeable when listening to Ambitonz Az A Ridah by Tupac and listening to the bass in Labyrinth by Mondo Grosso. And the Nano also has what I can only describe as a slightly fuller sound to it whereas the K3 is leaner. If we look at the features of both products, the Fiio has a lot more to it with the option of Coax out, Optical out, a USB Type C input, a bass boost option and a balanced input. Whereas the Nano BL on the other-hand provides a digital input, Line Out, two filters, and an IEMatch input, which is an attenuator that adjusts the? OI if am getting that correctly. Overall both products are great. But with a price difference and the feature set of the Fiio being a bit more comprehensive, the K3 is my pick.

    K3 vs. IFI Micro IDSD BL ($110 USD vs. $599 USD)

    This was a very similar experience overall with? the Nano. When listening to Thriller once again, the K3 provides a wider soundstage and field for imaging. The differences in soundstage was especially noticeable with the opening of the song. On the other hand, the Micro provides a smaller soundstage in comparison, but there is a greater sense of depth when listening to the footsteps and the imaging is also more precise. If we move on to bass with Mondo Gross and Tupac, the K3 is out performed here. The bass is better in all regards even with bass boost of the IFI. The K3 produces a less controlled and less refined bass. When listening to Shiver by Lucy Rose, the guitar in the beginning had a greater sense of reverb and body to it that I did not notice with the IFI. The major reason for the price difference comes down each product’s feature set. The IFI Micro provides a significant amount more power, which is something that the K3 will never come close to providing. The IFI also provides the ability to act as a pre-amplifier on-top of the plethora of gain settings. The K3 is a wonderful unit and is something more suited for a budding audiophile. While the IFI does a lot more in every way, it is not something that I need, so I once again would take the K3 over the IFI Micro IDSD BL.

    K3 vs. MacBook Onboard Sound

    This segment will be fairly short, but I think a brief mention is necessary. All the songs previously mentioned were listened to again and I found that the K3 to be a better sounding product on all levels. The K3 provided a greater amount of dynamic range. It was a much cleaner sound with a lack of hiss. The highs were less harsh and relaxed compared to the the Macbook when listening to pop. The K3, with the edition of all of its features, is a good choice if you are considering moving onto something dedicated for music listening or want to experience for yourself if balanced makes a difference.

    Conclusion and Closing


    Overall, I highly endorse the Fiio K3 especially, at its price point. It is a wonderful portable product that can cover the desktop needs of many people. It provides a healthy number of features at its price point without producing a sound that will not bother anyone. It is a very accessible product and is a good item? to begin with if you are interested in getting started on the audiophile journey. The only exception to the great value of the overall package is the shoddy cable provided. Something I would have liked to have seen would have been the ability to power the unit separately and use the optical as an input rather than just as an output.

    If you have a chance to try it, let me know what you think. The last thing I would like to say is enjoy the music and find what makes you happy.
      rantng and voxie like this.