Fit and Comfort

Seen above is the right channel of the FiiO FH7S placed into an artificial ear mold with the size M FiiO HS18 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 with some IEMs, and I am a big fan of these new FiiO tips for reasons previously mentioned. The size and shape of the FH7S shells was about perfect for my ears, depicted by the photo above, and I reckon most with average ears or larger will be plenty fine. Smaller conchas can potentially struggle with a snug fit, but the inner surface of the IEMs is a gentle slope to where you would still get a decent seal even if you feel them being slightly loose. The IEMs weigh ~9 g each to where it's slightly above average but the ergonomics help prevent physical fatigue. I will also give a shout out to the angled MMCX connector housings that allow for the pre-formed ear hooks to be more comfortably placed above and going around the back of the ears for further support. The MMCX connections also allow for the cable to be rotated freely around the IEM shells too, which is an advantage over 2-pin connectors in my books when executed out. The semi-open nature of these IEMs also means there is no pressure build-up inside and they don't affect the seal much either. Overall, as long as your ears can accommodate them, there is a good likelihood of achieving good passive isolation with a comfortable and secure fit.

Audio Performance

Audio Hardware

FiiO experimented with multiple dynamic drivers in the FH5s to middling success and have gone back to a more reliable single DD, multi-BA formula with the FH7S. The current FiiO hybrid IEM flagship FH9 also ends up being an inspiration, in that the dynamic driver used here is the same large 13.6 mm diamond-like carbon (DLC) diaphragm unit catering to the lower frequencies. The mids are handled by custom Knowles DFK-class dual balanced armature drivers and the higher frequencies by the Knowles SWFK-31736 dual tweeter BA drivers to make for a 1 DD/4 BA configuration here. Note the tweeters being placed in the nozzle that have the potential to be shouty, but the filters/dampers should help alleviate this—more on this later on. The FiiO FH7S is overall fairly average in terms of power requirements, owing to its average rated impedance of 18 Ω and sensitivity of 104 dB/mW. As such, just about any clean source can drive these easily—including your favorite phone dongle using the 3.5 mm connector if you don't have a source with a 4.4 mm balanced output. A portable DAC/amp might not be a bad idea if its within your budget—especially if you want to go with a Bluetooth option—or even a DAP for portable use. If not on the go, space is less of an issue, but the relatively short cable might still be a potential handicap if using a PC as the audio source.

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 connects to 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 the sound card. 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 FH7S. 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 within +/-1 dB of each other all the way, until well past the coupler resonance where things have to be taken with a grain of salt. As such, if we were to go by this randomly picked retail sample, I would be left quite pleased. 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 very well too, which is also an indicator of how good the seal was when installed in the artificial ear that could fit these.


Here is the average frequency response for both channels of the FiiO FH7S 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 difficult to quantify. Note also that I have all three tuning filters represented here which, as suspected, really only affect the higher frequencies by damping the in-nozzle BA drivers to various extents. What this ends up doing is, by comparison, throw the balance of the FH7S's tonality one way or another to where if the bass filter was used, for example, then the treble response is slightly lower in SPL compared to the balanced one, to thus make the bass region be more elevated by comparison. This is also the reverse with the treble filter as seen above. It's a slight change but enough to where the FiiO FH7S gives you leeway in customizing the overall tonality to one you prefer and then leave it as-is. Tuning switches, as with the FH5s we saw before, are easier to change on the fly but are harder to execute reliably, based on my experience.

I'd characterize the overall tonality of the FiiO FH7S as V-shaped on the balanced filters which is what I will be mostly using for the course of this review. In an age where Harman-centric tuning or even simply warm-neutral tonalities are increasingly commonplace, I do appreciate FiiO going with a more premium offering of a bassy and bright set. This also immediately makes the FH7S more suitable for some music genres than others, and I also would not recommend it for music monitoring or any other application where neutrality and accuracy is a must-have. Indeed, the bass response can be overwhelming for some, owing to not only a boomy but also punchy bass here with an 8 dB rise from the lowest point at ~800 Hz. I thought the FH7S plays well with electronic music without emphasizing faster notes, in addition to bass guitars where you do feel the twang of the strings moving back and forth. The mids are hit-or-miss here though, and I personally would not use the FH7S for more vocal-centric music, that takes a backstage to instruments regardless of how well the achieved fit is. Instrument separation is adequate but not class-leading, and in general the presentation here comes off overly smooth at the expense of detail retrieval.

On the flip side, this smoother and "musical" experience works well when you realized the FH7S provides one of the most spacious soundstages for IEMs ever! Indeed, I can't easily recall another set that bests this for the out-of-the-head experience when you have an orchestral recording or even opera music with higher pitched vocals seemingly reverberating around your room. This also helps reduce the potential for female vocals coming off shouty, owing to the upper mids elevation here. Imaging is excellent in a wide cone around the ears but less so in the imaginary central channel in front of you. Timbre is so-so with string instruments but drums thankfully come off more natural. The higher frequencies are well-represented but there wasn't anything particular standing out here. The relatively worse resolution means highly complex/fast jazz or classical music can feel somewhat wanting on this otherwise safe treble response.

Comparisons

The obvious comparisons would be against other entries in FiiO's FH hybrid IEM line including the previously covered FH5s, which the FH7S improves upon almost universally in fit and finish in addition to tonality and technical performance too. The FH5S, which I realize now after experiencing a lot more IEMs, has issues with a muddy bass and shouty treble which the damped FH7S with a more mature V-shaped tuning gets around. There's also the FHE:Eclipse, which is a bass-boosted FH3 but I thought I'd rather talk about some more unique hybrid driver IEMs here in the form of the DUNU VULKAN with its 2 DD/4BA and the Audio Hekili with a rare 1 DD/7 BA configuration. The VULKAN is similar in that it deviates from a neutral response and detail retrieval in favor of offering excellent mids reproduction, so it ends up complementing the FH7S as opposed to competing directly against it, despite being closely priced. You'd have to really choose based on what type of music you listen to more! The Audio Hekili is a very interesting 1-man project that is way more detailed and is more universally pleasing in tonality but can be sibilant and fatiguing to where it's not a set for everyone either. I can certainly see a world where the FH7S reigns over all three once you consider the larger sales channels and the relatively opulent accessories provided.


Then again, there are a bunch of other 1 DD/4 BA hybrid sets I have here, including the ThieAudio Legacy 5 with its emphasis on accuracy and a fairly flat tuning, as well as recently released enthusiast flavors of the month in the form of the Yanyin Canon and JQ 4Upro that will be covered soon. The Canon, as with the 4Upro, goes with a warm neutral tuning but adds tuning switches to change the overall sound signature in many different ways. It ends up being somewhat frustrating to cover since, ultimately, the drivers themselves are so-so and all these various options only go so far. It's the JQ 4Upro that is the real competition, with a simple, comfortable design that is easy to listen to for hours, and also costs nearly half that of the FH7S! Once again it comes down to what type of presentation and tuning you are looking for, but my personal pick would go the JQ route for the increased value for money. I will also mention that the tonality of the FiiO FH7S looks similar to a few other popular IEMs such as the MOONDROP KATO, but it still sounds different with a V-shaped signature as opposed to warm neutral.