Fit and Comfort

Seen above is the right channel of the FiiO FA19 placed into an artificial ear mold with the pre-installed size M silicone ear tip installed. I have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. Size M silicone tips are my go-to for testing, since foam tips are not included by some brands and I generally don't find foam tips agreeable for their sound signature. I mentioned before how the FA19 is thicker than average and will likely jut out of your ears as a result, although the other two dimensions are more tenable in terms of fitting in the ear concha and this is more important from a fit and comfort perspective. The shells have a semi-ergonomic design which also helps, as does the part where the inside of the shells has smooth curves and a reasonably sized and angled nozzle too. Those with average sized ears and ear canals should not have issues with the FA19 as a result. The shells weigh ~6 g each to make for a low density and minimize any potential of being physically fatiguing. The pre-formed ear hooks combined with the relatively supple cable and the freely rotating MMCX connectors also help provide additional points of contact and support for the IEMs, although I do wish the housings were more extended as the cable juts up too soon for my preferences and has to be rotated further back to avoid clashing with the top of my ears. The vent in the shells help prevent pressure building up in the ear canals to where I had no issues in terms of physical comfort for longer periods of time while still maintaining a good fit and seal. For what it's worth, I did try out some of the other ear tips too and still found the stock balanced tips to work best for me.

Audio Performance

Audio Hardware

The FiiO FA19 has a total of 10 drivers per side in an all-balanced armature driver configuration. FiiO has a good connection with renowned BA driver manufacturer Knowles, so it wasn't a surprise to see the FA19 go with just Knowles drivers too, even if this does mean the price tag is likely to be higher than other IEMs using less expensive BA drivers from some other brands. There are two custom dual-BA woofers (for a total of four drivers per side) handling the bass alone with the goal being to provide detailed and impactful bass. The shells are deliberately designed to have a tube feeding the acoustic energy from these drivers to the rear cavity, lowering the resonant frequency and creating more of a subwoofer-style sound too with deep reaching bass. The front cavity being vented also helps provide airflow and reduces any build-up of pressure in the ears. Two Knowles ED-class balanced armature drivers are responsible for the mids and FiiO has implemented a notch filter to help reduce any sibilance from these drivers by effectively dampening the high-frequency output of these drivers. The filter also increases 1-3 kHz energy to avoid the mids coming off hollow, and should also help with a more natural segue for the crossover leading to the treble tweeters from ~3.5 kHz on. Here we see two dual Knowles SWFK tweeters (four per side) thus making for a 4+2+4 BA 3-way crossover aided by expensive Rubycon film capacitors. FiiO is making sure you realize this is not a cheaply manufactured set, and this likely also means the FA19 is one of the more expensive FiiO products in general. That said, the FA19 is still extremely easy to drive with a low rated impedance of 10 Ω and average sensitivity of 106 dB/mW (@1 kHz). As such, any decent portable DAC/amp is plenty here, as long as they have a low output impedance, and I really don't see the point of going overboard with more powerful gear.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm-neutral signature with a slightly elevated bass, smooth treble range, detailed mids, and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear that IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running, and the earphones connected to the laptop through a capable and transparent DAC/amp—I used the FiiO KA5 here. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/12th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the appropriate ear mold fitted to the audio coupler for a separate test to compare how the IEMs fare when installed in a pinna geometry instead of just the audio coupler. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the rated frequency response in the FiiO FA19. The left channel was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two channels are very similar to each other across the entire useful 20 Hz to 20 kHz range. Keep in mind that resonance peak matching at~ 8 kHz can introduce some measurement artifacts and I can't say I really perceived the supposed imbalance in the 3-6 kHz to be honest. Some of this could be real though, since we know there is a crossover between the mids and treble drivers in this region, but ultimately channel imbalance is going to be less of an issue here as we will soon see. Measurements taken after 50+ hours of testing, which included these playing a mix of various songs as well as white or pink noise and sine sweeps, showed no difference. There was no perceived burn-in effect thus, and none was measurable, either. The response with the anthropomorphic pinna in place matched the ideal scenario in the coupler extremely well too, and here too I need to point out such a good match is atypical since the insertion depth can change how the resonance peak and frequency response thereafter behaves, even with the fact that these couplers aren't the most accurate in this range.


Here is the average frequency response for both channels of the FiiO FA19 plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. This is in addition to a second graph using a newer target that's based on a more scientific methodology involving a -10 dB tilt (-1 dB/octave) applied to the diffuse field target for the newer, more reliable B&K 5128 but then compensated for my exact 711 coupler instead. Do scroll down to the targets in my database linked above and see the new 5128 section to the left where you can click on the yellow question mark for a brief primer. The bottom line is this target is closer to what many people are likely to prefer out of IEMs and headphones alike. I have chosen to plot this graph with the frequency response normalized/compensated to the target to make it easier to see how the FiiO FA19 is tuned with the two modes on offer.

The FA19 ships with the switch off by default in its so-called monitor mode. I typically associate a monitoring set of IEMs to be more neutral and accurate sounding, although it is obvious the FA19 is certainly colored and adopts a more esoteric tuning. It's warm with mid-bass and lower mids emphasis followed by one of the better looking measurements in the upper mids and treble alike. In theory, I can see how someone would look at the graph and think FiiO is certainly striking at the more expensive flagship sets which cost a lot more. I also appreciate that FiiO is not just doing its usual take on V-shaped sound or even going for a neutral w/bass boost tuning that is all-so-common these days. Unfortunately, the actual implementation is somewhat lacking here, and you either immediately notice it or it can take a lot longer, depending on your music library. The issue is with the treble tweeters here which seem to be quite disjointed from the rest of the drivers. I can't tell if the notch filters are to blame here, but the crossover from the mid BA drivers to the treble BA tweeters should have been better handled. I could feel piano keys and string instruments come off quite unnatural as a result, and yet a single 2-step EQ profile helped so much. I simply raised 3-4 kHz slightly and added a negative shelf filter from 5 kHz onward, and now the FA19 not only sounded more cohesive but also significantly better throughout. I wanted some more upper mids to complement the warmer lower frequencies in the first place, although adding more 1-2 kHz felt like it was impacting soundstage and imaging to an extent.

Now I was back on board with FiiO's tuning, at least for the monitor mode. The bass is on point and hits harder than you might think for an all-BA set. It's still slightly loose, but this could be said across the spectrum and makes for a wide and tall soundstage to compensate for those who prioritize this. The monitor mode also keeps the mids from being bloated and muddy while having enough energy to help with bass guitars and drums alike, although turning the switch on to "HiFi mode" changes all this. While you do get more bass, it feels like more of a mediocre thing at best and instrument separation and detail retrieval all take a hit now in contrast to what this mode is named. Perhaps it's worth trying out if you are in the mood, and it may also be handy if you find the treble extension to be too much, but it has far too many compromises to be amenable. Going back to the monitor mode, The mids don't feel recessed thankfully, and I have to say vocals are a strong positive on the FA19—expect crisp and natural sounding voices that are in the forefront, be it male or female artists alike. Some instrument classes are better handled than others even with EQ, and more so out of the box. String instruments in particular are a weakness whereas most brass instruments and percussion hits fare better. As a result, the FA19 is better suited for certain music genres than others, and here too I can see why FiiO is trying to target TOTL sets to an extent by aiming to appeal to those who already know what they like in their music. The issue is that I am not convinced the FA19 excels at those TOTL-class technical qualities, be it timbre or detail retrieval.


The FiiO FA19 finds itself in one of the most competitive markets in recent years, including the ThieAudio Monarch MKIII which offers several shells and faceplates to go with its tribrid driver configuration. The Monarch MKIII is a more exciting take on the neutral w/bass boost tuning its predecessor went for, although this does mean alienating some of the audience with its increased bass and treble. Some also feel the dual DD setup was being let down slightly with its subwoofer-style bass shelf, so I do see why the Monarch MKIII isn't for everyone. At the same time, it's tuned more like a set of monitoring earphones than the FA19 and works better for more music genres too. The FA19 bests the Monarch MKIII for vocals reproduction, imaging, and soundstage though, and certainly offers more accessories. Then there's the versatile 64 Audio U4s which remains my recommendation in this price range. It's more comfortable, built with all aluminium shells, offers linear impedance to avoid any issues with source output impedance, and has support for Apex modules to allow for a customizable bass shelf. Both the FA19 and U4s trade blows when it comes to detail retrieval, meaning either are really that good at it, but the U4s is more to my liking for tuning as well as the other factors mentioned. FiiO does win out on the accessory front again, which isn't hard compared to a 64 Audio offering, but it doesn't do enough to win this comparison from the pure sound output front. The Custom Art FIBAE 5 is another tribrid with an esoteric tuning as well, and it uses Knowles dampers to affect the bass shelf—funny how three of the four sets here have a customizable bass shelf and all three use different methods to achieve the same. The FIBAE 5 might alienate people with its more extreme treble response, but the FA19 isn't that far off, and I dare say the FIBAE 5 does this tuning style better than FiiO did too. None of the other three sets here have the coherence issue that the FA19 does with its mids-to-treble crossover either.