FiiO FH15 Review

FiiO FH15 Review

14 February 2023 2 By Petros Laskis

FiiO FH15 Review

The smooth operator

Pros: + Balanced and organic sounding with great timbre and plenty of musicality
+ Great bass extension with ample dynamics
+ Smooth and forgiving treble
+ Can be fine tuned with the three sound tubes
+ Spacious soundstage with accurate imaging
+ Lightweight and comfortable with good passive noise attenuation
+ Good quality modular cable
+ Plenty of accessories and eartips

Cons: – Bass is not neutral and not suitable for critical listening
– The bass can sound a little hollow and bloomy
– Not the best performer in transparency and resolution
– Some people might find the treble as too subdued
– The soundstage is narrower than the FH5S
– A 2.5mm plug is missing from the modular cable

The review sample was kindly provided free of charge in exchange for an honest review.
I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links.
The price of the FiiO FH15 is $229 and you can order it from here.


FiiO FH15

The FH15 is FiiO’s new hybrid in-ear monitor that introduces the company’s brand new naming scheme that is a little bit confusing to memorize.
This is literally the successor of the FiiO FH5 and FH5S.
You can read about the new naming scheme in the following illustration.


Anyway, back to the FH15, the configuration consists of 3 BA drivers together with a single dynamic driver.
Equipped with a brand-new 10mm dynamic driver with carbon-based diaphragm, the FiiO FH15 features excellent transient performance. In this device, the carbon’s lightweight, strong rigidity and high internal resistance means that the dynamic driver can quickly start and stop movements when responding to changes in the input signal.
For mid frequencies, the FiiO FH15 employs a custom Knowles ED BA driver which works in conjunction with specially placed tuning holes in the shell.
Treble is handled by 2 Knowles RAD BA drivers, which are capable of high treble resolution and capture every last detail in the music, for a truly airy sound.
The FH15 also features a custom-made notch filter.

A Helmholz resonator is designed to work with the mid-frequency drivers. When the soundwave is at a particular frequency that the Helmholz resonator is designed to work with, the volume of sounds with this frequency is enhanced as the resonator concentrates and resonates that frequency. Additionally, the resonator is connected to a thin opening to eliminate any unwanted resonance peaks and overlapping frequencies produced by the different drivers, in order to achieve better coherence among the drivers while also eliminating sibilance.
The FH15 also employs FiiO’s S.Turbo patented design and comes with three interchangeable sound filters for a slightly different sound signature.
Red filter is for enhanced bass, black for balanced sound and green for exquisite and highly resolving treble.


Design, fit and build quality

The FH15 utilizes an aluminum alloy construction, which when combined with the dragon scale design elements allows the shells to have a unique and exquisite look.
This new type of housing is an evolution of the one found in the F9 Pro (do you remember them?) and has a relatively low, rounded profile that follows the contours of the ear offering a very comfortable, stable and stress free fit that is aided by the lightweight construction.
The new design is much better looking and comfortable than the previous generation housings of the series while the closed back design offers very good passive noise attenuation.
Build quality is simply excellent, the finish is flawless and smooth while the earshells look super durable.



The FH15 comes with a 152-wire silver plated monocrystalline copper cable featuring 8 strands of Litz-braided wire and MMCX plugs.
The Litz braiding specifically reduces the skin and proximity effects, leading to reduced eddy current losses and thus improved high-frequency resolution.
Additionally, the audio plugs are swappable, and included are 3.5mm and 4.4mm plugs but not a 2.5mm that is still commonly used.
The cable is of high quality with aluminum plugs and splitter, it has very low microphonic noise and it doesn’t get tangled.



As always with FiiO you get a great assortment of accessories.
Except for the cable and the sound tuning filters you also get a standard plastic carrying case, a MMCX removal tool and a cleaning brush.
The ear-tips include the brand new HS18, balanced, bass and vocal in three pairs each, two pairs of dual flange and two pairs of memory foam ear-tips.
An all inclusive and pretty amazing package for the price.


Driving Efficiency and associated gear

The FH15 has a 16Ω of rated impedance with 112dB/mW of sensitivity so they are very easy to drive and you can use them straight out from your phone’s headphone jack.
Of course you can do much better with an entry level DAC dongle like the FiiO KA1 or for the best results you can use something like the FiiO KA3 or M11S because the FH15 scales pretty well and will reward you with great sound.


Listening impressions

The FH15 is a smooth, balanced and full sounding IEM with a touch of cozy warmth and a rather forgiving treble.
It is very musical sounding with natural timbre and great sense of realism.
There is great sub-bass extension followed by a tastefully emphasized bass that extends into the mid-bass but not too much as to severely affect mid-range clarity and presence.
You can tame the bass a little bit by using the treble filter and the HS18 ear-tips but the latter will also affect the weight of the texture with the result of a drier and leaner sounding bass which otherwise is full bodied and visceral.
The bass is dynamic, contrasted and impactful with plenty of punchiness but it can sound a touch hollow and a little slower than ideal.
Nonetheless, it is mostly controlled and tight with plenty of shading and excellent definition for the category.
Simpler classical works will sound good but with more demanding symphonic works where the bass line gets busy and complex, the FH15 will sound a touch one-noted without too much layering and definition.
The tonality is not that off-pitch, you can equally enjoy bass heavy and acoustic tracks without too much coloring.

The transition from the upper-bass to the mids is smooth without veil but there is a certain lack of transparency and clarity that disappears as we climb higher the range.
The integration between the two drivers is coherent and the mid-range doesn’t sound detached relative to the bass.
The tuning is balanced and natural with a convincing tonality and a lifelike quality to the voices and the instruments.
The overall clarity is satisfying, the mids sound articulated, full bodied and present with good refinement and plenty of harmonic wealth albeit not that well defined and airy for critical listening.
The FH15 has an easy tuning without frequency exaggerations, it is easy to the ear and warm without sibilant or shouting vocals.


The same qualities apply to the treble which is quite safely tuned for a smooth and forgiving listening experience but without sacrificing in extension and resolution.
The FH15 is in no way veiled or dark sounding, there is plenty of energy and crispiness to keep things moving, detail retrieval is very good for the category but there is a certain lack of endgame resolution and transparency.
This is not necessarily bad because not all people like bright, analytical and treble forward sounding earphones so if you belong to this category you will be well served.
The treble filters make for a crispier and more energetic treble performance but they also add a couple of peaks that induce some kind of harshness and I ended preferring the balanced filters but your mileage may vary and you are welcomed to experiment.
Something of special mention is the excellent implementation of the drivers that don’t sound detached or out of phase with the result of a very cohesive frequency response.
The FH15 unlike its predecessor, the FH5S, is of a closed back design so the soundstage can’t reach the openness and wideness of the latter.
Still this is an open sounding earphone with a moderately expanded soundstage which is not by any means narrow or claustrophobic while it has a very satisfying positioning and separation.
The FH15 served me pretty well for non-critical everyday listening of classical music, especially with less demanding material like Mozart’s early string quartets.


Compared to the FiiO FH5S ($250)

The bulkier and open back FiiO FH5S wasn’t received very well because people weren’t patient enough to allow plenty of time for the dual dynamic drivers to break in.
Sadly, because after that it is an excellent sounding earphone with a high quality, neutral, extended and technically strong bass, an engaging and transparent mid-range and a touch of forward and very energetic treble response with fine resolution and plenty of clarity.
Not to mention the super wide and spacious soundstage with the laser sharp imaging and the ability to fine tune the sound signature with the aid of the electronic crossover.
As you can probably understand these are two earphones that step into different sound directions with opposing sound signatures and it is not that difficult to pick your favorite one.


In the end

Musical, engaging and organic sounding with a nice touch of warmth, great tonal balance and good technicalities for the category, the FH15 is addressed to all of you who are treble sensitive and want an easy listening and non fatiguing earphone suitable for everyday listening with all types of music.

Test playlist

Copyright – Petros Laskis 2023.