Fiio FD3

Fiio FD3 is a new semi-open, single 12mm dynamic driver IEM with a recommended price of $99.
Price Driver Impedance Sensitivity


Fiio is a commonly known brand in the audio market. Their product catalog is very wide and in my opinion, everyone can find something for themself. From desktop DAC/Amps to IEMs with prices starting at $15 for toy-ish Fiio F1 to $499 for 6 Knowles BA in Fiio FA9. The reviewed model – FD3 is a lower-midrange representative of Fiio’s single dynamic driver IEMs family. They have quite an experience with 1DD IEMs in the past, and its previously released FD5 is both superb looking and good sounding, which makes it a really successful model. Let’s see how it went this time around.


Fiio FD3 arrives in a very nicely designed, big box with a lot of accessories. Inside you will find a hard, waterproof Peli-like case, four different types of tips, an additional pair of interchangeable sound tubes, a cleaning brush, an MMCX assist tool (a small thing, but very useful when you’ve never disconnected the MMCX cable), the cable and of course FD3 headphones. As far as I know, the only difference between FD3 and FD3Pro versions is the cable, the pro version arrives with 8-stranded, silver-plated copper cable with three swappable plugs, while the “default” version is bundled with a 4-stranded copper cable with a 3.5 mm plug. 

The basic cable is quite flexible, the MMCX connectors hold the IEMs tight and everything looks quite durable. In terms of comfort, it’s way more comfortable than LC-B, which was shipped with e.g. Fiio FH3 and I would say that the FD3 cable is more comfortable than 8-stranded silver-plated Fiio LC-C.

Build Quality & Comfort

The earphones are nicely built, the faceplate is made of celluloid with a glass coating. The body is made of aluminum-magnesium alloy metal with interchangeable sound tubes. Overall the build quality is pretty decent, for the price it’s even more than I expected, but Fiio already taught us that they know how to build premium-feeling stuff at a relatively low price. The Fiio FD3 is pretty lightweight, small, and thanks to quite long nozzles, it can be very comfortable even for people with long entry to the ear canal. The biggest disadvantage might be that they significantly stick out of ears, depending on listener anatomy the IEMs might look even almost like Shrek’s ears, so if you like to listen to music while lying on your side, that’s definitely a bad choice. 

What’s important to emphasize once more, the reviewed IEMs have semi-open construction, which means that the noise insulation is on a very low level. For me, these earphones are perfect for cycling or running, but when you want to cut yourself from your surroundings, they won’t work well.


The FD3 uses a single 12mm dynamic driver with a 1.5m Tesla magnetic flux paired with an ultra-finecopper-clad aluminum Japanese Daikoku voice coil.

The diaphragm is made of Diamond-Like Carbon (DLC) which is both ultra-light and sensitive.

The body is made of a aluminum-magnesium alloy, and on the front there are unique celluloid panels covered with glass, which look absolutely stunning.  


Fiio doesn’t help reviewers in writing short reviews, each of the ear tips and filters sets makes them sound different, but they have some things in common – the bass and midrange provide a lot of meat, of course, if you want to receive this effect, you need to drive them properly, but on the other hand even plugged to a phone, they sound fine. I think that they can be amazing for novices in the audiophile world, now you can start with only one IEMs, but when you will try them with a better source, you will figure out that you don’t need it, but the life with good DAC/amp is more vibrant and just better. 

The bass is definitely the most forwarded part of the frequency range. Maybe it’s not as amplified as in Campfire Audio Honeydew, but if you’re not looking for earphones for bassheads, you won’t like Fiio FD3. As I mentioned above, it’s full and whitened. It’s easy to spot that the dynamic driver is responsible for reproducing the sound. Maybe it’s not the fastest bass reproduced by Fiio’s IEMs, but maybe it’s because after listening to Craft Ears Aurum I won’t be able to say this about any other earphones. In the song you should see me in a crown by Billie Eilish the bass is terribly well controlled, I could not only hear but almost feel the low frequencies, and damn, it works wonderfully. 

The midrange is heavy, pretty well-textured, and superbly engaging. In songs where midrange is the main course, it’s never too loud to listen to. Especially driven with SMSL SU-9, which also provides some juice, the vocals are very natural and have an amazing body. The vocals of The Fairfield Four in These Bones are hypnotizing, I could put this song on repeat, listen to it the whole evening and I wouldn’t get bored. But if you’re a fan of acoustic guitar, there is also something for you, the lower midrange is very punchy and well-built so guitars played by Rodrigo and Gabriela sound amazing, and Fiio FD3 are superb for reproducing their album Mettavolution. In my opinion with this setup – balanced ear tips, bass sound filters, driven by SU-9 + SP200 I would never say that the midrange can be realized so good in such inexpensive headphones. 

Now onto the treble. Well, do we have to focus on that part of the frequency range in these headphones? To be honest when for the first time I had put them into my ears, I thought “what the hell? Fiio, did you forget to put trebles into my headphones?”. FD3 are definitely not the best pick, when you’re looking for cold, analytical and crystal treble, they are definitely on the warm or very warm side. The higher end of the range is definitely recessed and it doesn’t want to get in the foreground, but on the other hand, it’s very forgiving for the bad quality of mastering. Yet another time I will base my review on remastered Californication by Red Hot Chilli Peppers because I think that everyone should stigmatize how good music was destroyed by terrible mastering. But back to Fiio FD3, because Ear-Fidelity still focuses mostly on hardware. While listening to Californication I can hear all the issues, but it’s not as aggressive as when listening to this track on FH3, or Audio-Technica M50x, I would say the treble is quite pleasant.

The soundstage is quite narrow, but let’s be honest, it’s hard to find a $99 IEMs which can be proud of creating a wide soundstage, I would describe it as a decent width for the price. But when properly driven, I mean PROPERLY driven it’s getting more interesting, for me it’s hard to define, but something between depth and height of soundstage is really impressive. As I mentioned above, a lot of power can make them sound spectacular, but I’m afraid there aren’t many madmen, who will plug quite cheap IEMs into a mid-end and very stationary combo like SP-9 & SP200. I did it, and if you have a possibility, you should also try to plug them into something like this desktop setup, but Fiio FD3 powered with something more portable also can sound quite good. These are my impressions of FH3 sound with accessories that were attached to the headphones taken straight out of the box, but as I mentioned before, the package contains four different sets of ear tips and additional sound filters. 

The light tips with red tubes called by Fiio as “vocal tips” make the sound brighter, the bass just slightly recessed when compared to the default tips. The dark tips with red tubes, which are called by Fiio as “bass tips”, for me should be called treble killers. With red filters they remove the rest of the details in the sound, my suggestion is to throw them out, or if you really want to use them, do it only with black filters. The last and the least (at least for me) are memory foam tips, for me, they are very uncomfortable, I can’t stand using them for more than 30 seconds and I’m not able to focus on sound, it’s just impossible. The tips change the sound signature only a bit, but with sound tubes, it changes a lot. The bass is getting slightly less powerful. It’s still the most highlighted part of the frequency response, but a little less than with the red filters. The midrange is also recessed when compared to the bass tubes, but the biggest difference is in the treble. With the black tubes which are made for “detailed treble” the highest part of the frequency range is realized completely differently. Especially with the vocal tips, the sound of the Fiio FD3 changes into almost a V-shaped signature. There appears a lot of details, but unfortunately, this also helps to detect all mix and mastering issues of the listened track. In this setup, the reviewed headphones become more analytical, but still with very powerful bass and pretty decent midrange. For me, the FD3 works the best with red sound tubes and neutral or vocal tips, but black tubes with bass or neutral tips also work quite well.




Vs Fiio FH3

Fiio FH3 is a hybrid IEM with two balanced armatures made by Knowles and a single dynamic driver with an MSRP at $129, but now it’s possible to find them discounted at about $100 which makes them the natural rival of the reviewed earphones. But first, let’s move back to July 2020, when Fiio released FH3. I thought that’s strange that they made a model that sounds better than almost twice as expensive as the FH5 and do you know what? They did exactly the same thing in their single dynamic driver IEMs line-up, FD3 is a more interesting option than FD5. That’s the first thing in common between FD3 and FH3, second is the bass – if you liked the way the hybrid earphones reproduces the low frequencies, you will also like how the new IEMs work. Now let’s move to differences, first is audible when we focus on the midrange, it’s definitely recessed in FH3 when compared to FD3. On the other hand, the trebles are way more highlighted in hybrid IEMs. When I compare the soundstage, the one reproduced by FH3 is “rounder” and wider, but not as deep as the one from FD3. In short words I would say that this comparison is between darker, but not too dark bass-midrange single dynamic driver headphones and quite analytical with v-shaped frequency response hybrid ones. For the sake of comfort, for me, the rounded shape of FH3 is way more comfortable, but this part is very subjective and depends on many anatomical factors. For me, there is no clear winner in this comparison, just two different, but complementary IEMs and if you’re not sure which you need more, just take both – it will be cheaper and better than FD5, or FH5.


KZ ZSX is a hybrid IEM with five balanced armatures and a single dynamic driver on each side with a $50 MSRP, but if we add a better cable and ear tips (the accessories included in the package are terrible) the expenses are getting close to the FD3 price. The sound signature of KZ is V-shaped, especially the midrange is very, very recessed when compared to the Fiio earphones. What’s interesting is that compared to ZSX the soundstage presented by FD3 is splendid. When switching between these two earphones it’s way more audible than I would expect. The last thing worth mentioning is that Fiio IEMs are way more forgiving in terms of the signal source, KZ ZSX connected to mid-end phone jack produces a lot of noise vs FD3 which are almost completely quiet. In this comparison the winner is easy to pick for me, the only reasons that can justify picking ZSX over FD3 are comfort, sound isolation, or that you currently don’t have enough money and you need IEMs for now and you will buy the accessories next month.



The Fiio FD3 is yet another great release from this brand. If you are looking for universal, but fun-focused IEMs under $100, you should definitely take them into consideration. Their biggest disadvantage is weak sound isolation, which makes them not as mobile as I would expect IEMs should be, but if you will remember about it, you definitely won’t regret anything else. Very interesting pair of IEMs priced really reasonably – what’s not to like?

Gear used during this review for the sake of comparison and as an accompanying equipment:

  • Headphones – Craft Ears 4 CIEM, Craft Ears Aurum UIEM, Fiio FH3, Fiio FH5s, KZ ZSX, Kinera Nan-Na, Campfire Audio Solaris 2020, Campfire Audio Ara
  • Sources– SMSL SU-9 & SP200, Fiio M11pro, Fiio btr3k