Review: FiiO FH15 in-Ear Earphone

Review: FiiO FH15 1DD 3 Knowles BA Hybrid Technology in-Ear Earphone with 3.5mm/4.4mm MMCX Cable

The FiiO FH15 is based on single 10mm dynamic and triple Knowles armature drivers. The headphones have replaceable acoustic filters and a modular cable made of silver-plated monocrystalline copper.

The name suggests that the FiiO FH15 is positioned higher than the flagship FH9, but none of these things because it is the successor of the FH5 models and potentially the FH5s / FH5s Pro. However, the “Fifteen” have more in common with the older FH5 because there is also a single dynamic driver and three armature drivers per channel. However, this time the sound can be returned, but not with the built-in equalizer, as in the FH5s, but with classic acoustic filters.

I did not expect the new “average” premiere in the FiiO offer because the FH5s and FH5s Pro debuted relatively recently. These are successful hybrids based on double dynamic and double armature drivers. I especially liked the second model with a better-chosen cable because the FH5s Pro are, in my opinion, the most cost-effective FiiO in-ear headphones. So I was curious about what the FH15s had to offer and whether new hybrids were needed.


Set contains:

  • 3 pairs of FiiO HS18 tips (sizes S, M, and L);
  • 3 pairs of Vocal tips (white and red, sizes S, M, and L);
  • 3 pairs of Balanced tips (grey, sizes S, M, and L);
  • 3 pairs of Bass tips (grey-red, sizes S, M, and L);
  • 2 pairs of double-flange tips (size M);
  • 2 pairs of thermoactive foams (size M);
  • tips box;
  • MMCX cable with Velcro (silver-plated OCC copper, approx. 120 cm);
  • modular plugs (3.5 mm and 4.4 mm);
  • tool for removing MMCX plugs;
  • acoustic filters (bass, balanced, and soprano);
  • filter mold;
  • headphone box;
  • cleaning brush;
  • User manual and documentation.

The equipment is similar to the FH7s model, but SpinFit tips, a magnetic band, and a case made of artificial leather have been abandoned, which in my opinion, is survivable. After all, the manufacturer adds its own HS18 tips, Velcro band, and a plastic box for headphones. In turn, the cable this time is two-core but also made of silver-plated OCC copper.


FiiO FH15 stands out from other FiiO in-ear headphones because the housings are teardrop-shaped this time. However, the characteristic champagne-gold piping, which brings to mind the classic FH5, has returned. However, in place of the waves, there are … “dragon scales,” i.e., rhythmic, rhomboid depressions. Although the design is secondary, I think the FH15 is a step back – I prefer the angular FH5s Pro or even the FH7s. There is also a lot missing from the rounded FH9 or minimalist FH3. The build quality, however, does not raise any objections because the headphones are milled from aluminum and precisely fitted.

The lids are not ventilated, but there were vent holes – one accompanies the MMCX socket, and the other is located on the inside of the headphones, right next to the channel marking. The gold-plated MMCX sockets have been distinguished by colors – a red ring means the right earphone and a blue ring means the left. Interestingly, green acoustic filters, i.e., soprano ones, were installed at the factory. These are just metal meshes, inside which there are no additional inserts, unlike the red (bass) and black (balanced) filters.

The cable has similar parameters to that of the FH7s model because it is made of 152 strands of silver-plated OCC copper. However, in this case, they were twisted not into eight but two strands. As a result, the earbud sections are not ribbed but smooth, which also applies to temples with MMCX plugs. The latter is full of colorful accents, corresponding to the rings around the MMCX sockets. On the cable, there is also a flat splitter with an additional slider and the already well-known plug with a detachable collar that allows you to replace the cartridge. There are 3.5 mm and 4.4 mm standards to choose from.

Ergonomics and use

The FH15 are comfortable headphones mainly due to the rounded casings. I think they are more pleasant to the touch than the angular FH7s. The headphones are also smaller than the FH5s, so they almost do not protrude from the ears and do not expand the auricles. The bushings are optimally long, so no mistake was made with the older FH5s. The sound insulation is also satisfactory – the environment can still be heard but is heavily muffled so that we can focus on the music. In my opinion, the FH15 dampens better than the vented FH5s Pro or FH7s.

The new cable works well too. The cable fits well, and the temples have been optimally bent, so they stick securely to the auricles and do not cut into the skin. In turn, the slider at the splitter maintains the selected position, so it allows you to stabilize the cable on the auricles additionally. There is a slight microphone effect, but it is not noticeable. When I moved my head or while walking, I could hear the cable brushing against my clothes, but only in silence because the sounds did not cut through the music.

Tips FiiO HS18 raise some doubts. This time they did not turn to the other side when removing the headphones from the ears, which I complained about in the test of the FH7s model. However, I had problems getting the correct seal because the thin flanges of the tips deformed in the ear canals, which did not fill them correctly. I had to put on the headphones appropriately shallow, otherwise, I lost the seal. Therefore, although the original tips resemble SpinFit, they do not match them in terms of use.


  • drivers: dynamic DLC 10mm (bass) + Knowles ED (mid) + 2x Knowles RAD (treble)
  • frequency response: 10Hz-40kHz
  • impedance: 16 ohms
  • sensitivity: 112 dB
  • cable: silver-plated OCC copper, MMCX > 3.5 mm/4.4 mm (approx. 120 cm)
  • weight: 6.3 g (single earphone); 33.3 g (headphones with cable, tips, etc.)


FiiO FH15 – tips
I believe most of the tips in the set are unsuitable for the FH15. The treble was too calm with the older FiiO tips (Vocal, Bass, and Balanced) and foams. Traditionally, I could not check double-flange tips because my ear canals are incompatible.

So the HS18 tips were the best because they offered the clearest, but not harsh sound. I also tried SpinFit CP-145, which also matched the headphones, also slightly brightening them. Too bad they were omitted.

FiiO FH15s – green (soprano) filters
FiiO FH15 have little in common with the FH5 or FH5s/FH5s Pro because the sound signature has changed – the headphones are musical, maximally smooth and warm because they have been accentuated in the low tones, and calmed down in the upper registers. There are some similarities to the more expensive FH7s, but there is no question of direct tracing because the FH7s offer a more extended treble. As a result, the FH15s provide an entertaining signature, engaging with sound and relaxing when the repertoire demands it. However, I think that not everything went according to plan, which will be discussed soon.

Low tones are the main course. No, the headphones are not extremely bass, but the bass plays the first violin; it is dense and massive. The FH15 goes low into the sub-bass, does not limit the mid-bass, and does not cut the mid-bass. The headphones can therefore purr low, good juicy, and warm in the low tones and hit quite hard, which is especially conducive to electronics or popular music, but also to heavy guitar sounds. The bass is not fast, but I was satisfied with the dynamics, attack, and long sustain. I noticed, however, that the bottom of the band is relatively smooth and soft, and its texture is not exceptionally differentiated. You can still hear the details and easily distinguish the instruments from each other, but the priority is musicality.

The midrange has a warm, smooth, and saturated character, so the lower range has more to say. The upper midrange was not erased because the contour of the sound is not entirely blurred, but I do not doubt that it plays a supporting role. The midrange seems softened, rounded, and softened – not even a trace of sharpness can be heard. To be honest, I sometimes forget that I am dealing with hybrid headphones because the FH15 does not sound aggressive, demanding, or harsh at all, which can often be accused of armature drivers. Fans of a clear message will be happy, but others may turn their noses up. For me, the midrange was not clear enough, I lacked “claw” in the music, more robust high vocals, more aggressive drums or guitars.

The highs are … gentle and smooth. Maybe the frequency range is not entirely cut, and the sound is not dark yet, but you can already hear the roll-off in the highest octaves. There is no question of a strong, perfectly extended, crystalline treble, which can be assessed in two ways. On the one hand, with the FH15 in the ears, it is easy to relax because the headphones did not tire me for a moment, and I did not have to worry about sibilation even in poorly produced music. On the other hand, I missed a bit of “fitting,” a more direct and clear presentation. It can be heard that the manufacturer used this “notch” again, i.e., a new filter that calms the upper registers. I think it worked great in the clearer FH7s, but in this case, it seems redundant. After all, shortcomings in the treble occur in the factory configuration, i.e., with soprano filters,

The soundstage is ellipsoidal and has optimal dimensions and proportions. The channel separation is impeccable, so the music spreads to the sides. The foreground is close, but there is no effect of being surrounded by sound or tightness. This is also due to the excellent depth and height of the space because the instruments are also exposed on the front-back and top-bottom planes. The virtual sources are also quite shapely and more three-dimensional than flat because the FH15 is a hybrid design. There are no large distances between them because the nooks and crannies are filled with bass, which forms the foundation of the sound, but the individual instruments do not yet merge.

FiiO FH15s – black (balanced) and red (bass) filters
The other filters are redundant, in my opinion. I did not feel the need to boost the bass, cut the treble additionally, or “even out” the sound. In my opinion, the green filters should be called bass or, at most, balanced, and the additional ones should brighten the sound. Therefore, The tuning system does not fulfill its role; it does not seem to be adapted to the headphones’ signature.

It also turns out that the impact of the other filters is subtle. I probably wouldn’t distinguish green filters from those black ones that are supposed to be balanced. Both types of filters provided a similarly smooth treble, saturated midrange, and free bass. The green ones were slightly clearer than the black ones. In turn, the red filters additionally strengthened the bass, which was more willing to go ahead of the line but was not significantly boosted anyway. So we have a choice of mild (green), softer (black), and even softer (red) filters.

So I decided to… completely unscrew the filters. This is not recommended because dirt can get directly into the sound tubes, and the lack of a filter shortens the sleeve, making the tips stick worse. Nevertheless, in this way, I obtained a more transparent, tonally neutral sound with accents in the band’s extremes, bringing to mind the original, i.e., the old FH5. The FH15 should sound like this with soprano filters; then, equalizing the sound or boosting the bass would make sense.

FiiO FH15s – comparisons with the FH5s, FH7s, and other FH5s and FH5s Pro headphones sound more precise, contoured, and natural than the FH15. I perceive the models of the FH5s series as a harder outlined sound, closer in the midrange, and better-differentiating instruments. The FiiO FH15 are much smoother and noticeably warmer than them. In the case of the FH5s/FH5s Pro, the armature drivers have more to say, despite the presence of double dynamics. The sound of the FH15 is, therefore, more accessible and much safer but less expressive and satisfying. Personally, I would choose the FH5s Pro because the FH15s are too smooth for me.

The FH7s generate more highs than the FH15s and are more tonally neutral because they are V-tuned. There are similarities in the bass, but the FH7s have a more varied and dynamic low end that is springy and shows off the attack. In a confrontation, the lows of the FH15 tend to be sluggish – softer, smoother, and less energetic than those of the FH7s. The FH7s are technically better, but they are about PLN 1,000 more expensive than the FH15. However, the “fifties” may be a cheaper alternative to the fully dynamic FD7, which represent a similar sound philosophy, because they also sound soft, smooth, and warm.

And how do the FH15s compare to cheaper models? Letshuoer S12 was the first to go, i.e., planar in-ears, which were also warm and smooth, but did not limit the treble so much. In my opinion, the S12s also provide a bit more information, better differentiate the textures of the instruments, and at the same time still engage with low tones, full and massive. The same applies to the BQEYZ Autumn (musical, but harder to outline the sound), and the Spring II (definitely brighter, but less accessible).

FiiO FH15 – synergy
These headphones need synergy. I recommend combining them with brighter or, at most, neutral sources because I got the best results with players based on ESS Technology chips. The more precise and technical the source sounded, the better the FH15s responded. The best were Astell&Kern Kann Max, FiiO M17, or  M11 Plus ESS, and worse, FiiO M11s, M15, or Cayin N3Pro.

Signal purity is also essential because the headphones are effective and have low impedance (112 dB and 16 Ω). For example, although Kann Max was synergistic with the headphones, it did not provide a sufficiently clean signal – in the quieter parts of the tracks or between them, there was noise. For this reason, less efficient Bluetooth adapters like the FiiO BTR7 or Qudelix-5K worked better than the players, with which the signal was clear.


FiiO FH15 does not disappoint with performance, ergonomics, or capabilities because they are modular hybrids. The set is rich, the new cable does not raise significant objections, and the headphones also attenuate well. The sound is musical and highly relaxing – massive bass and smooth and mellow sound are the hallmarks of the FH15 model. I also did not like the optimally wide and deep sound stage.

Cons are primarily subjective. The new HS18 tips did not suit me, and they matched the headphones best. The transition between the upper midrange and the treble is too gentle, making the sound warm, dense, and maximally smooth, so it does not suit my taste. For this reason, additional filters do not make much sense because they only increase the gentleness of the headphones.

Personally, without hesitation, I would choose the older FH5s Pro instead, which is still musical but sound more complex and more precise, and offer a more effective sound tuning system. However, if we are sensitive to the treble and are looking for a rather consumer tuning, the FH15 may be better. On the other hand, people who want to replace the FH5 may not be satisfied because the FH15 is a sonic 180-degree turn.

+ rich equipment
+ solid workmanship
+ high ergonomics
+ modular cable
+ replaceable acoustic filters
+ good attenuation
+ soft, warm, smooth and pleasant sound with deep bass
+ wide soundstage

– too soft treble (even with green filters)
– suboptimal sound tuning system
– not very detailed, a bit too bland bass