FiiO FD7 Review

FiiO FD7 Review

22 October 2021 0 By Petros Laskis

FiiO FD7 Review

A flagship devoted to music

Pros: – Balanced, musical and engaging
– Very natural and organic timbre
– Excellent bass with thunderous dynamics
– Wide open and holographic soundstage with top imaging
– Smooth and transparent treble
– Comfortable fit
– Pure silver modular cable of high quality
– Comprehensive accessory pack
– Aggressively priced

Cons: – Sub – bass lacking in extension
– Needs absolutely high quality partnering sources
– Long “burning” time as suggested by the manufacturer
– Average passive noise attenuation
– Fit is not very stable
– The bass tuning nozzle lacks in control

The FiiO FD7 was kindly provided free of charge and I only covered import taxes and fees.
FiiO never asked for a favorable review and this is my honest and subjective evaluation.
The links are not affiliated and I don’t get commission by clicking on them.
The FD7 selling price is €599.99 and you can buy it from


There is an on going frenzy about single Dynamic Driver iems, it seems to be the vogue now and FiiO is already into the game.
They have inaugurated their FD line with the FD5 (review), followed by the entry level FiiO FD3 and now they have released the flagship FD7 together with a special collectors edition called FDX.


Technical highlights

The FiiO FD7 is equipped with a large 12mm dynamic driver unit that utilizes a pure Beryllium (and not beryllium coated) diaphragm coil.
Pure Beryllium Diaphragm offers splendid performance with swift mobility and sturdiness.
The new flagship 12mm pure beryllium diaphragm dynamic driver, due to beryllium being 4 times more rigid than steel while only weighing 14 as much as titanium, has 3 times the transient performance compared to titanium drivers for lightning-like speed and thunderous explosive sound.

Close to the pure beryllium driver in the FD7 is an acoustic prism system that addresses issues that come with the time delay between different sound waves.
It effectively changes and precisely controls the way sound waves travel through the FD7 to enhance how high frequency waves propagate and to ensure audio phases are correct.

The ingenious “volcanic field” system developed by FiiO takes advantage of how sound waves work to noticeably improve its sound.
The “volcanic field” reduces standing waves and distortion, and overall improves the diffusion of bass waves in the FiiO FD7.
In addition, the FD7’s semi-open design relieves pressure on the ear for more comfortable listening.


Interchangeable sound tubes

Befitting of its flagship status, the FiiO FD7 comes standard with three pairs of interchangeable sound tubes, each with a different inner diameter for different sounds.
The large inner tube presents a vast soundstage, the medium inner tube impresses with its balanced sound, while the smallest inner tube serves up explosive bass.

Build quality and appearance

The FD7 shells are made from a solid block of stainless steel, carefully carved through a 5-axis CNC-milling process.
The build quality is top notch, the MMCX connectors look very sturdy and the finish is smooth without any visible spots.
In contrast to the glossy design of the FD5 the FD7 features a matte black “gunmetal” color with golden accents at the mesh.
They are very beautiful looking, reminding more of a jewel than an iem plus they offer a discrete fit.


Fit and isolation

The shape and dimensions are the same as with the other FD series iems, weighting 11gr per earpiece that is the same as the FD5 and a little heavier than the 7gr of the FD3.
Despite being rounded with that barrel-like design they actually fit very well and are comfortable, offering a stress free listening experience.
If there is a drawback is that you can’t get a very steady fit so I wouldn’t recommend them for exercise but anyway I don’t see many people buying them for this use.
The bass enhancing tube is of narrower diameter so it may not offer the same kind of fit and some users would reach for the triple flange ear tips to get a better fit.
The semi-open design results in medium passive noise attenuation but it is not that bad as it sounds and increasing the volume a little will compensate for it but anyway you should get the most of the FiiO FD7 in a quiet environment.



The FiiO FD7 comes standard with a high-purity monocrystalline pure silver cable in Litz braided style.
Four large strands in a total of 224 wires are braided together in one cable.
The wire sheath is made of environmentally friendly medical grade TPU to resist yellowing after long-term use and against stiffening when in low-temperature environments.
And it comes with twist-lock interchangeable audio plugs for the 2.5/3.5/4.4mm sizes for ultimate convenience.
The twist-lock system is the most sturdy and future-proof design so I prefer it over twist or snap to fit.
The cable of the FD7 was designed with angled expanded MMCX connectors which went through many ergonomic iterations and improvements in order to achieve maximum wearing comfort.
The cable is absent from microphonic noise and offers excellent handling experience, it is a very high quality cable worthy of a flagship iem and some aftermarket cables of this quality cost more than the FD7 itself.


Accessory pack is premium and with the FD7 you get the LC-RE(+) cable with 3.5mm, 2.5mm, and 4.4mm termination plugs, the new HB5 high quality storage case, three sound tubes screwed in a metallic card, an MMCX extraction tool, 6 bass eartips, 6 balanced eartips, 6 vocal eartips, 6 Spinfits, 2 triple-flange tips, and 4 foam tips all organized in a foam holder, a cleaning brush
and a magnetic cable organizer.


Listening set-up, power requirements

The FiiO FD7 is rated at 50Ω with a sensitivity of 111dB so while it is more difficult to drive than the common iems it isn’t much of a challenge and all medium powered devices should be enough as long as they can provide some extra headroom.

Quality of course is another matter and make no mistake the FD7 is very demanding of it because it scales incredibly well and it is very transparent so you are going to need a high quality source in order to fully exploit its potential.
Give it something mediocre and it will sound as such, then switch to something great and you will be impressed with the results.
In other words you are going to need at least something mid tier like the EarMen Sparrow and the THX Onyx and then work your way up to higher tier like the FiiO M11 Plus and iBasso DX300 or even better something like the Cayin C9 which I was fortunate enough to have it on a loan and I was blown away with the performance.


Burning time

A few notes about the burning process, be a believer or not the company suggests that the FD7 pure beryllium driver needs at least 150 – 200 hours in order to break in and sound as intended.
Don’t jump into rushed conclusions and please follow the instructions before you reach your final verdict.

Sound impressions

As per my usual practice, I avoid browsing into frequency response graphs since they tend to be deceiving and negatively affect my subconscious so I prefer the old school reviewing method of intensive music listening.

While waiting for the FiiO FD7 driver to break in I couldn’t help myself reading various FD7 performance impressions to discover the hype that was building around it so I decided to forego my usual test tracks for a hardcore and stronger first challenge.

Nothing more stretching than Mahler’s second symphony in this interpretation by Daniele Gatti.


The first opening bars were enough to establish a deep and strong impression about the FiiO FD7 personality and pave the way for what it was going to follow in the next few weeks.

The symphony starts with an ominous tremolo on the violins followed by cellos and low C double basses marching arpeggios that pose a great challenge regarding the low end performance.
In tune, full bodied, with weighty notes and exemplary layering, sharp attacks into the strings, well defined bowing, all these combined with top notch clarity which helped the following contrabassoon single-note statement to be clearly heard instead of being mashed by the double basses.

Then they enter solo cor anglais with oboes in a duet singing a mourning melody supported by blazing and glowing muted brass, leading after a short episode of violin lyricism into the first climax where we can hear the cymbal decaying with perfect timing and weight.

Throughout the whole symphony all instruments sounded with the most natural and convincing timbre that I could imagine, very close to reality not only in respect to the tuning but also for the textural quality.

The symphony’s intensive harmonic complexity was clearly reproduced with exemplary coherency throughout the whole frequency range.
I was able to follow the multi-layered instrumentation and enjoy the myriads of tone colors that flooded my head, pouring out from dozens of different instruments from the bigger timpani, to the singing flutes, the pastoral bells and the well articulated voices that entered in the last two movements.

All instruments sounded clear and defined while the FiiO FD7 was resolving and detailed enough as not to miss a single note.
The masking effect was totally absent and every single instrument was clearly heard even while soloing pianissimo notes in the background of a large orchestra.

An orchestra, one of the largest available but the FD7, was able to stress the scene into a three dimensional plan with holographic projection and pinpoint accuracy, not only between individual instruments but also clearly defining the various instrumental groups.
Dimensionality aside, we also need to stretch our vision into time and the FD7 proved able to do so by communicating the sense of inner space and reverb of the recording venue, capturing the past and applying it into the present.

Another favorite piece that I use for checking dynamics is the percussion concerto “Siedi” by Kalevi Aho.


The concerto opens with a dialogue between solo djembe and the grand bass drum.
And the FiiO FD7 was able to capture all the thunderous dynamics of the bass drum hits and not only the control of the crushing strikes but also the reverb of the concert hall, while at the same time maintaining excellent clarity and speed to correctly present the lighting fast and well defined finger tapping of the djembe soloist.

The examples can continue for ever and make this review quite long but I can’t help not mentioning a couple of more.

The Carmen Fantasy by Pablo de Sarasate was a good test to check the decay of the high pitched percussion instruments with the introductory tambourine hits that sounded brilliant, shimmering, full bodied and not too rushed.
Then after some chords on the harps enters the solo violin that was reproduced with plenty of harmonic wealth and a clear rendering of the various bowing techniques that are used throughout the piece.


The next example is a vocal quartet “Voglio Tempo” by G.F Handel for soprano, mezzo – soprano, alto, tenor and orchestra, a good track for checking vocal integrity and timbral saturation of the mid range.


The orchestra was widely arranged and the singers were precisely positioned from the left to the right with plenty of space between them.
All four were tonally presented with the same gravitas and I was able to hear and enjoy the specific tone color of each singer.
The da capo section starts with the high soprano improvised cadenza reaching the limits of her vocal register, a stress exercise that can easily expose sibilance, harshness and ringing but the FD7 was absent of them and reproduced the full tessitura of the voice without sounding dull or muted.

One final example is the second scherzo in B flat minor by Chopin, a very challenging piano piece not only for the performer but also for the transducer.


The FiiO FD7 proved one more time to be excellent sounding as it reproduced the rich harmonic palette of the grand piano, the intense hammering of the strings, the fast arpeggios, the sudden dynamic changes, the pedaling effect, the furious scale runs, the attack and decay plus the timbral complexity of the instrument.

So to sum everything up, the FD7 offers a flagship level performance that concentrates around coherency, realistic timbre, natural tonality and texture quality without giving up too much in technicalities.

The overall tuning is close to the objective ideal by the means that all acoustic instruments must sound close to reality.
This is a subjective hobby and we all have our welcomed preferences but there must be an undeniably established objectivity about how transducers should be able to reproduce voices and unamplified instruments as close to the truth as it is possible.
This is the reference point from where we must start and then deviate according to our tastes and the FD7 sits very close to this ideal.

As you have noticed the review concentrates around classical music and this is done on purpose to highlight the musicality and organic nature of the FiiO FD7 but rest assured that it can easily cope and satisfy with all kinds of music as long as you don’t like a mannered and manipulated sound approach, in such case you should look for something else.


A few notes about the sound tubes

The three sound tubes share the same overall sound signature with some differences here and there to tailor the sound to your needs.
I have decided for the reference tube with the balanced ear tips but the other two also yielded interesting results, sacrificing something in favor of something else.
The larger nozzle adds just a little bit of treble emphasis and sparkle at top giving the impression of a more open and detailed sound but slightly losing on timbral quality and texture.
The narrower tube doesn’t enhance the bass but rather greatly rolls off the treble to give the impression of a boosted low end.
The takeaway is that it robs the highs of their energy, becoming more dull and also negatively affects the quality properties of the bass that becomes a little boomy and less controlled.
Further combinations can be done together with the various ear tips to micromanage the sound in order to better suit specific sound preferences and music genres.


Compared with the Sennheiser IE900

Disclaimer – The IE900 was returned before I started the FiiO FD7 evaluation but since I used it for more than two months continuously I feel confident to do a brief comparison.

The Sennheiser IE900 is tuned with a gentle emphasis on the low end that adds real sub – bass extension, that is lacking from the FD7, and at the same time slightly boosts the lower bass above the reference point.
As such it can sound more lush and full bodied – compared to the leaner FD7 – and it will offer more satisfying experience with electronic bass, greatly pleasing the fans of the genre but at the expense of acoustic low bass instruments that will sound quite off tone and slightly mask the higher pitched members of the family like the cello.

The IE900 is amazing and top notch when it comes to quality characteristics and technical performance of the bass but the FiiO FD7 holds on its own without lacking either while there is a certain point where it takes the lead.
The FD7 larger driver can move great amounts of air and despite all the high – tech tricks that are employed inside the IE900, I am afraid that it comes second when we examine dynamic contrast and thrust with the FD7 giving more thunderous and slamming bass effects that fill not only the ears but the whole head of the listener.

Another key difference in tonality is that the IE900 has a more V-shaped tuning with recessed upper mids, as a result it sounds more distanced and not so engaging as the FD7 which in contrast feels more liquid and saturated in this region.
There is some brilliance emphasis that is used to add clarity, treble sparkle, enhanced detail retrieval and compensate for the extra bass boost tuning of the IE900.
The tuning is very ingeniously executed by the IE900 designers, so it manages to sound considerably more detailed, finer and resolving than the FD7 – without becoming analytical – but the penalty is that it slightly loses in timbre, gaining a metallic hue, becoming thin and with rushed decay while it is prone in becoming hot with certain material when the FD7 remains always smooth and controlled.
Both earphones share the same musical approach and excellent timbral qualities but in my opinion the FD7 has a small lead as it sounds more cohesive and natural from top to bottom.


Lastly there is a key difference between the two regarding the overall sound projection so when we compare them, the IE900 gives the impression of a reduced scale, the listener is like seated in the gallery watching to the spectacle from a distance and above while with the FD7 is positioned about third row in front of the orchestra and the experience feels certainly grander and larger in scale with more natural proportions.

At the end

The FiiO FD7 is an audiophile’s dream; musical, engaging with superior timbral and textural qualities yet transparent and technically accomplished, it offers a holistic listening experience very close to reality.
If you have associated a flagship iem with extreme technicalities, hyper detail retrieval or some kind of specific tuning then the FD7 is not meant for you.
All others rest assured that the FD7 is worthy of an end game, flagship status and that comes at a very modest asking price.
Music listening is about sentiments, the continuous two way communication between the recorded performance and the listener with the headphone as the intermediate and the FiiO FD7 is a master of the trade.

Test playlist

Copyright – Laskis Petros 2021