FiiO FH9 Review

FiiO FH9 Review

20 December 2021 0 By Petros Laskis

FiiO FH9 Review

Guilty pleasure

Pros: + Big and bold with real sub bass extension and explosive dynamics
+ Fun and exciting
+ Clear and well defined mids
+ Smooth yet extended treble
+ Detailed and crystal clear
+ Flagship level of technicalities
+ Open, spacious and out of the head soundstage with precise imaging
+ Excellent build quality
+ Masterpiece cable
+ Full accessory pack
+ Quite comfortable despite the size

Cons: – Low end is too dominant
– Mid bass is lacking in clarity and layering
– A little more technical than musical
– Quite bulky and heavy
– Medium passive noise isolation

The FH9 was kindly provided by FiiO free of charge, I only covered import fees and taxes.
As always this is my subjective and unbiased review.
The price is €699 and you can buy it from


FiiO’s hybrid line of earphones is distinguished from the letters FH and the available models are named FH1s, FH3, FH5 (now OP), FH5s, FH7 and the brand new FH9, the latest flagship hybrid driver in-ear monitor.


Design features

FiiO has designed the FH9 with a seven-driver hybrid configuration on each side.
The pair houses a 13.6mm 2nd generation DLC diaphragm dynamic driver, one of the largest to be found in an earphone, paired to six premium balanced armature drivers designed by Knowles.

The FH9 is FiiO’s first hybrid IEM to feature a self- developed 2nd generation DLC (diamond-like carbon) bass driver.
Compared to the 1st generation driver, the magnetic circuit structure has been redesigned resulting in 20% higher magnetic density to better push the massive 13.6mm DLC diaphragm – which means an even more dynamic sound.
And thanks to DLC’s outstanding rigidity and high damping coefficient, the FH9’s bass driver is capable of providing extremely quick transient response with extremely minimal distortion.

All 6 BA drivers in each ear unit of the FH9 are from Knowles.
High frequencies are handled by three of the proven SWFK -31736 drivers.
For the mid frequency drivers, FiiO has partnered with Knowles themselves in over 2years of extensive research on how to best implement such drivers to achieve perfect harmony between multiple drivers for an absolutely coherent sound.


The FiiO FH9’s shell is specially engineered to eliminate unwanted harmonic resonance generated as sound waves travel through the shell, sound tube and cavity – which greatly eliminates undesirable sibilance in the sound.
FiiO has designed the cavities for FH9 based on their latest-gen industrial-grade design.
They feature precisely crafted CNC machined Titanium alloy ear cavities. The Titanium-alloy construction is extremely rigid and helps to minimize the unwanted harmonics and resonances in the output signal.
Each FH9 unit is made with great precision using a five-axis CNC machining process.

The FH9 features a semi-open acoustic design incorporating FiiO’s patented system of balanced pressure relief between the front and rear cavities.
The result is more natural sound, and more comfortable listening in longer sessions due to greatly minimized pressure on your eardrums when listening.

FiiO FH9, like most of their latest earphones, comes with three interchangeable sound filters, each filter has its own damping and filter density.
They help adjust the sound a little bit, and can be used as per the user’s preferences.
The pair comes packed with a red filter for enhancing bass response, a green filter for transparent and balanced sound and a black filter for highly-resolving detailed treble sound.



Included with the FiiO FH9 is a high-purity pure silver cable with 8 branches of 28 wires each, for a total of 224 wires.
Each wire is individually isolated and all are braided together in the Litz style.
The outer sheath of the cable is made from environmentally friendly TPU, which not only sports a radiant transparent look but is also resistant against yellowing under long-term use and stiffening when in low-temperature environments.
The stainless steel angled MMCX connectors are designed to make the wearing experience as painless as possible.
Details such as the special angle allow you to more easily connect your IEMs for more comfortable wearing as well as the left blue right red indicators to quickly get you going.
The cable features the interchangeable plug system so the user can use it with a multitude of devices without the need to use adapters.
The package includes 3.5mm, 4.4mm and 2.5mm plugs.
The included cable is a masterpiece and such aftermarket cables usually cost more than the FH9 itself.
Excellent and congratulations on FiiO for including such a high-end cable at this price.



When it comes to accessories, FiiO is number one in providing the customer with everything that is needed for a complete listening experience.
The buyer along with the FH9 gets the following:

HB5 carrying case*1
Bass ear tips*3 pairs (SML)
Balanced ear tips*3 pairs (SML)
Vocals ear tips*3 pairs (SML)
Foam ear tips*2 pairs (M)
Double -flange ear tips *2 (M)
SpinFit eartips*3 pairs (SML)
Cleaning brush*1
MMCX removal tool*1
Magnetic clamp*1
Green/Black/Red audio filters*1 set
2.5/3.5/4.4mm interchangeable audio plug*1 set
8 strands of 224 wires each high-purity monocrystalline pure silver cable*1


Wearing comfort and isolation

Too many drivers need a larger housing to accommodate them, so the FH9 is quite bulky especially when compared to some single dynamic driver Iems like the FiiO FD7 or Sennheiser IE900.
Thus said, the shells are anatomically designed with an extended nozzle that helps with deep and snuggle insertion while the shell rests into the outer ear without causing any extra annoyance.
Despite the increased weight (12.8gr per unit) I would rate the fit as comfortable but the user will not fail to notice that there is something large snug in his ear and while the design is beautiful and contemporary, the FH9 is not the most discrete earphone.
Needless to say that the FH9 is not suitable for outdoor activities and exercise not only for the fit but also for the semi – open design which doesn’t help a lot with passive noise isolation.
It is not that you can’t use it outdoors but you better avoid some very noisy places.


Build quality

Build quality is excellent, this is one of the best – if not the best – earphones that I have ever laid my hands on.
It is premium and classy with top notch finish and the most excellent craftsmanship, the same goes for the cable which is simply top tier, from the interchangeable plugs, to the braided design and the aluminum MMCX connectors.
Kudos to FiiO for the excellent job.


Listening impressions

I left the FiiO FH9 playing music for more than 200 hours but I haven’t bothered to observe if there were any sound changes, I have just started listening after that period of time.

The FH9 are rated at 18Ω@1kHz with a sensitivity of 108dB so they don’t pose any significant requirements for driving them.
But while they can get pretty loud from most portable sources, the user must remember that they are a set of transparent and revealing flagship earphones so a good quality source is a must.
I have mostly used the FiiO M11 Plus along with the iBasso DX240 and DX300.

Upon starting the listening sessions my first move was to swap the pre-installed Spin-fit ear tips for the balanced ones.
I don’t know about you but I never had good results with the Spin-fits as I find them to be too forward sounding for my liking.


The first impression is that of a huge sounding earphone with top notch clarity across the range and a bass dominant sound signature that thankfully doesn’t end up masking the rest of the frequencies.
And when I say huge, I mean really huge, like listening to some great open back headphones, the FiiO FH9 is the most spacious and grand sounding iem I have tested till now.
And bassy, really bassy as the FH9 has bass-head level emphasized low end, starting from the sub-bass and extending to the upper-bass.
I am not talking here about mere frequency response but rather about the style of the overall presentation.
In the FH9 the dynamic dynamic driver is the dominant force, the one that sets the pace, it is like a giant standing above the armature drivers blocking the sun out of them, letting them dwell under his shadow.

Macro dynamics are utterly impressive, the bass is so full bodied and thumping that it gives the most realistic impressions while sub-bass kicks like there is hidden a subwoofer inside the FH9.
The bass is not lacking in quality as it is tight, controlled and fast but due to the excessive mid-bass coloring the end result is lacking in ultimate clarity, the bass line gets masked and layering is not as satisfying at least when considering reference standards.
So from now on we must split the listening impressions in accordance with the music genre and the listener preferences.

Fans of electronic music, RNB, modern pop and such will be jumping in their feets from joy, oh boy the party is on and the night is still young and full of possibilities.
Listening to the “Disco” album by Kylie Minogue is a pure joy thanks to the punching bass and her fine voice which is expressed with clarity and outstanding articulation without getting lost in the mix.


The mood gets even higher with bass beating re-mixes where the listener feels like being in the club dancing to his favorite tunes.


The FiiO FH9 also excels in movie watching or listening to your favorite soundtracks.
The experience is reminiscent of a well calibrated multi-channel home cinema system.
Watching the “Black Panther” movie and then listening to the title “OST was utterly impressive with exploding and earth-shattering action scenes.


On the other hand with more reference friendly material like the “Cello Concerto” by Eduard Lalo, the solo cello was more intense and forward-sounding than it should be, overpowering with its presence the delicate orchestral accompaniments.
Even more in the large orchestral tutti the bass instruments sounded too dominant and thick, lacking in ultimate layering and definition that is needed in order to clearly pick every single note of each individual instrument, especially when playing at a different dynamic range.
As an example, it gets quite difficult to hear “ppp” bassoon playing under the dominant “fff” double basses and cellos.


Thankfully this mild masking phenomenon is only effective as far as the dynamic driver frequency range goes and from the point where the balanced armature drivers kick in, everything stays clear, unaffected and well defined, as such the FH9 manages to sound cohesive and comprehensive despite the bass dominant sound signature.
The mid-range is mostly neutral tuned with good presence, well articulated voices and some fine sounding instruments with a natural timbre.
Texture is a little lean, more precise, airy and transparent, less rounded and organic, not as full bodied but it doesn’t sound artificial or clinical.
It is not the most musical presentation but it still gets communicative and enjoyable with all kinds of music but don’t expect a lush and mid – forward presentation.

Transition to the treble is exemplary with excellent integration between the drivers and nothing sounds detached or out of phase.
The tuning is smooth and stays under control but still extended and present, able to resolve some fine detail without sounding analytical.
The FiiO FH9 is tuned to the opposite direction of the forward-sounding FH5s, more relaxed and not too sharp but not as far as to sound muted or blunt.
It is balanced and natural sounding, one of the most musically tuned high frequencies in the FiiO stable, with good body weight, fine texture and even decaying but the attentive listener will not fail to notice the slightest hint of the so-called balanced armature timbre.
But I am nitpicking here and I have to admit that I am very fond of the FH9 upper frequencies response, especially with the “balanced” tube.


Sound tuning tubes

Users who prefer a more spicy treble presentation can switch for the “treble” tube which adds some extra sparkle, enhanced clarity and more presence with only a touch of brightness as a side effect, while it also helps for the bass to sound clearer and better defined.
On the opposite side the “bass” tube mutes the higher frequencies adding more heft and impact to the bass which however becomes boomy and less controlled but bass lovers will certainly appreciate the extra oomph and weight.



I am a little short of words to describe the FiiO FH9 soundstage which is one of the best available from an iem and rivaled only by the top tier, highly expensive competition.
The FH9 sounds more like a good open back headphone as it draws a soundscape that extends in front and around the listener in a very enveloping way.
Wide and extended but always natural and perspective, it adapts accordingly to the listening material, be it a solo instrument or a large symphony orchestra, always feeling open and spacious with accurate and precise imaging.
The overall feeling is holographic with good depth layering, high levels of transparency and excellent spatial cues, a truly remarkable performance that will make you forget about the semi open design and the lack of relative isolation.
Movie watching is awesome.


Compared to the FH5s

Unfortunately it’s been a long time since I have reviewed the FH7 and I wouldn’t risk a comparison so I will limit my impressions against the FiiO FH5S
The FH9 is almost two times the price of the FH5s but worthily so because it is better in various parameters.
Treble tuning is more balanced, leaving behind the FH5s sharpness for a smoother approach although with better micro detail resolution and better perceived extension.
Timbre is more natural and the drivers sound better integrated as a whole, leading to a more cohesive sounding experience.
Bass is not so overbearing on the FH5s and tuning is more neutral but the FH9 wins in overall technicalities and in the intensity of the presentation.
Also transparency, presence and definition are of higher caliber in the FH9 as is the spaciousness of the soundstage.
Thus said the FH5s is miraculously performing for the asking price and if you need a spacious, open sounding, highly detailed iem and you don’t mind the treble forward presentation then it is a great choice.


Compared to the FD7

The FiiO FD7 is a single dynamic driver earphone and is currently seated at the top of the FiiO “FD” line.
On first glance someone might think that a single dynamic driver iem can’t compete with a multi driver hybrid set but this is far from the truth.
The FD7 holds on it’s own with a more reference and balanced tuning and that is not only in the bass range.
Bass is more tight and controlled without any signs of masking or bleeding into the upper bass so the FD7 has higher layering capabilities and sounds more clear, precise and defined in the low end.
Of course it can’t compete with the FH9 in sub – bass extension or power and kick, you can’t party with the FD7 as you can do with the FH9 but on the other hand it can do much better in resolving complex bass lines.
Mids and treble are quite close regarding the overall balance and tuning, the FH9 is a touch more forward in the upper mids but the main differences that we should concentrate on are timbre related.
The FiiO team has done an excellent job regarding the integration of the FH9 multiple drivers and the final result is pretty homogeneous sound.
But still nothing can beat a good single dynamic driver when it comes to the integrity and cohesiveness of the frequency bands.
The FD7 is more accurate and precise with greater unity across the spectrum while the timbre is more organic, natural and lifelike with greater musicality.
In the end both earphones are great, certainly worth their flagship status and as always individual musical preferences should be the judging criteria for choosing the one over the other.
As an example the FD7 is unbeatable when it comes to classical music but I should prefer the FH9 for movie watching and some Disco tunes.


In the end

The FiiO FH9 is a great sounding iem with a huge, bold and spacious sound signature.
No, it is not a strict reference in it’s tuning but not everything needs to be tuned this way.
With explosive bass performance and an exuberant personality this a fun and utterly exciting earphone that without sacrificing in flagship level technical performance, is going to reward the happy owner with great moments of sheer (and a guilty one for some of you) pleasure.

Test playlist

Copyright – Laskis Petros 2021.