Fiio F9 PRO review

Fiio F9 Pro;

A Rich Sound in an Organic Design…



Many of us are familiar with Fiio Products; especially the Portable Audio Players of the X line up like X3, X5, X7 etc. Fiio joined later in to the earphone business with there first IEM that was called Fiio EX1. After the success of Fiio F9, they announced in November 2017 a new upgrade model called F9 Pro, which is the company’s second hybrid in-ear monitor (IEM) model, which i will now review for you.

About Fiio:

FiiO is a Chinese HiFi brand that was established in 2007 and has experience in researching and developing countless portable music products of different types, and sell FiiO-branded products through sales agents worldwide. The brand name FiiO is composed of Fi (fidelity from HiFi) and iO (number 1&0), representing the real feeling and convenient life that digital brings to life. Meanwhile, the Chinese “飞傲” is the transliteration of FiiO, indicating the positive and innovative spirit as thriving as spring.


I would like to thank Fiio for providing me the Fiio F9 Pro as free review sample. I am not affiliated with Fiio beyond this review and these words reflect my true and unaltered, opinions about the product.


The MSRP price for the Fiio F9 Pro is 139,99 USD.

Package and Accessories:

The Fiio F9 Pro comes in a small rectangle cardboard box, which is wrapped with a glossy paper sleeve which has some illustrations and specification on about the F9 Pro on it.

This box contains the following contents;

  • 1 pair x F9 Pro In-Ear Monitor
  • 1 x carrying case
  • 12 pairs x Ear tips (3 pairs of foam + 9 pairs of silicone)
  • 1 x 3.5mm single-ended cable with in-line controls
  • 1 x 2.5mm balanced cable
  • 1 x Water-resistant neoprene carrying pouch

The F9 PRO comes with three different types of silicone ear tips ((9 in totals) and one type of foam ear tips in small, medium, and large size, which are very comfortable.

The box contains one waterproof hard case/carry case, as well as a water-resistant neoprene carrying pouch. The hard case is made of a black glossy plastic material that has a very stylish design and a good form factor.

The neoprene zipper pouch is in gray and is quite useful with its small design.


Fiio F9 Pro comes with two types of MMCX (micro-miniature coaxial) connector cables;

The first cable is has an 3.5mm SE (Single Ended) headphone jack with a L-shaped plug that is made of a tin plated cooper material with TPU coating. This cable has a microphone with line-in control.

The second cable has a 2.5mm balanced headphone jack, which comes also with an L-shaped plug. The 4 core cable is made of 5N purity OFC (Oxygen Free Cooper) wire which is has also a black TPU coating.

Cables have nice stylish left and right markings. The left channel is adorned with a splash of blue, while the end of the right channel is trimmed with a red marking for an easy identification of the audio channels. These channel ends also have a spiral texture engraved into them.


Design, Build Quality and Fit:

The shell of the Fiio F9 Pro is made of aluminum and has a very ergonomic design. The outer surface sports a water wave like design which Fiio describes as “Organic Design”. The  inside layer of the F9 PRO’s shell is according to Fiio lined with plastic to both better secure the drivers and eliminate internal resonances.

You can find on the inner face of each monitor two bass vents, the L (Left) & R (Right) markings and the model description PRO. The angled nozzle of the Fiio F9 Pro is lipped and sports a fine metal filter on the top. The MMCX connectors have a solid appearance and should last for years.

The noise isolation of the Fiio F9 Pro is above average due the bass vents on the monitor, which are causing to a small amount of noise leakage.

The Fiio F9 Pro is quite comfortable due the relative small size and design shape. I was able to wear it for more than (approx) 2.5 – 3 hours without any discomfort.



  • Driver Type                 : Hybrid (1 x 9.2mm DD + 2 BA Drivers (Knowles TWFK-30017-000)
  • Frequency response   : 15Hz ~ 40kHz
  • Sensitivity                    : 106 dB/mW
  • Impedance                  : 28 Ω
  • Cord length                 : 1.2 m
  • Weight                        : About 3.76 g/per unit
  • Color                           : Titanium (with “PRO” mark on the Y-splitter and the earbuds)
  • Detachable Cables      : 1 x 2.5mm Balanced and 1x 3.5mm SE Cable with MMCX connectors


More about the Hybrid Driver Configuration:

The Fiio F9 Pro has 2 Knowles balanced armature of the model TWFK-30017-000 + 1 PEK polymer nanocomposite dynamic driver with 9.2mm diameter under the hood.

The Knowles dual balanced armature TWFK-30017-000:

 The Knowles dual balanced armature TWFK-30017-000 gives the F9 Pro immense capabilities in resolving every last detail, all in a truly powerful and overwhelming presentation of your music – the way it was meant to be heard.

The PEK Polymer Nanocomposite Dynamic Driver:

The F9 PRO utilizes a dynamic driver made of PEK (Polyether Ketone) polymer nanocomposite, known for not only being tough but also being light. This allows the F9 PRO’s dynamic driver to be lightly capable of producing quick, detailed and extended bass.


Drivability (Impedance):

The Fiio F9 Pro has an impedance of 28 ohm and is easy to drive. This makes it ideal for all type of portable Digital Audio Players (DAP’s). Even my Samsung Galaxy S8 could push the Fiio F9 Pro to very loud volume levels.


Albums & Tracks used for this review:

  • Martin Garix – Animal (Tidal Hi-Fi)
  • Daft Punk – Get Lucky (Flac 24bit/192kHz)
  • Lorde – Team (Flac 24bit/48kHz)
  • Michael Jackson – Billie Jean (DSF)
  • Future Heroes – Another World (Tidal Hi-fi)
  • Saskia Bruin – The Look of Love (DSF)
  • Diana Krall – So Wonderful (DSF)
  • Jeah Barbur – Seni Seviyorum (Spotify)
  • LP (Laura Pergolizzi) – Lost On You “Live at Harvard and Stone” (Tidal Hi-Fi)
  • George Micahel – Older (Tidal Hi-Fi)
  • Mile Davis – Kind of Blue Album (Tidal Hi-fi)
  • Dire Straits – Money For Nothing (DSF)
  • Emmanuel Pahud (Claude Debussy) – Syrinx (Apple Music)
  • Otto Liebert & Luna Negra – Up Close “Album” (DSF) – Binaural Recording
  • Alboran Trio – Autumn Mist (Tidal Hi-Fi)
  • GoGo Penguin – Fanfares (Tidal Hi-Fi)
  • Opeth – Damnation (Tidal Hi-Fi)
  • Megadeth – Sweating Bullets (Flac 16bit/44kHz)


Sources used for this review:

  • IEM                 : Fiio F9 Pro, iBasso IT01, TFZ TEQUILA1, Dunu Falcon-C
  • DAP/DAC      : Cayin N5II, Chord Mojo, Hifiman HM603s, Nexum Aqua+

The Sound:

Please Note: This review is written after a bun-in process of 120 hours. I have used the stock black silicone ear tips during this review that are included to the package.

a. Tonality and Presentation:

The Fiio F9 Pro has well balanced sound signature with a mildly recessed midrange, which sounds warmer then neutral. It is a quite dynamic sounding IEM with one of best resolution levels in this price range.

b. Frequencies:

The bass of the Fiio F9 Pro sounds quite natural in its presentation with a good amount of impact and rumble when it called for.

The sub-bass area between 20 – 50 Hz is well presented and has good body and weight, but doesn’t reach to the lowest register. The overall bass speed is pretty good and the sub-bass presentation in Martin Garrix – Animal sounds pretty fast and controlled, which makes it suitable for genres like electronic, rap etc. but not on a bass-head level.

Bass notes have more presence than sub-bass notes and this tuning gives the Fiio F9 Pro some nice dynamics without to make the sound too boomy in this frequency region. The transition between bass and midrange is also pretty well done, which is avoiding any muffled and veiled presentation of instrument and vocals.

The Fiio F9 Pro has a quite balanced (maybe mildly v shaped) sound signature as I mentioned before, where the midrange is slightly recessed. There is a good amount of air, where instruments have a nice sense of space without to sound too distance. This tuning allows Instruments to sound quite natural and gives it a clean and detailed presentation. The midrange of the Fiio F9 Pro has also some good texture and definition with some nice a level op transparency.

Both male and female vocals sounding quite natural and have a nice emotional presentation. But female vocals like Saskia Bruin, Jehan Barbur. etc. sounded in general a tad more delicious.

The upper midrange of the Fiio F9 is nicely presented, which sounded quite controlled in almost any track I have listened. I have heard only some stress, which was only noticeable in some instrument intensive passages with instruments like violin, cymbals, etc.

The treble range of the Fiio F9 Pro sounds a bit hot, but has a good level of clarity and detail retrieval. Also the treble speed and extension of the Fiio F9 Pro does a good job in some complex tracks like GoGo Penguin’s – Muration. The treble range of the Fiio F9 Pro is providing the overall sound a spacious presentation, which is a big welcome in this price range.

The treble range of the Fiio F9 Pro sounds quite detailed and has a nice level of resolution. The upper treble range doesn’t sound too bright and there is also no unnecessary boast that could cause otherwise to harshness and sibilance.

c. Soundstage and Imaging:

The Fiio F9 Pro is an airy sounding IEM with a relative wide soundstage. The stage has a good wideness but is missing of some depth. The overall performance for imaging and instrument placement is pretty good and is represented in a quite natural way.




Vs. Dunu Falcon-C:

The Dunu Flacon-C sounds more aggressively V shaped compared to Fiio F9 Pro, which has a more balanced tuning.

The Dunu Falcon-C has more mid-bass impact than Fiio F9 Pro, which sounds more balanced at the bass department. The overall speed and extension of the bass is nearly identical, but the Dunu Falcon-C’s bass performance is very fit depending and can vary from people to people. With a deeper insertion and the right ear tips, you can archive some nice rumble. The bass of the Fiio F9 Pro is tighter and has additional control.

The midrange of the Dunu Falcon-C sounds a bit thinner and more distant, but has good transparency and definition. The Fiio F9 Pro sounds slightly warmer and fuller at the midrange, which makes its vocal presentation more intimate. Dunu Falcon-C sounds a bit more airy than Fiio F9 Pro.

The Fiio F9 Pro has additional transparency and clarity in its midrange, but the overall resolution of the Flacon-C is nearly the same. The Dunu Falcon-C is missing some micro detail, due the more distant instrument presentation.

The upper midrange of Fiio F9 Pro sounds slightly more detailed and more controlled then those of the Dunu Falcon-C, which has otherwise a great performance.

The vocal performance of the Dunu Falcon-C is pretty good with male vocals, but some female voices like Laura Pergolizzi sounding a bit thin too for my taste where the Fiio F9 Pro performs more organic with its presentation. The Fiio F9 Pro has also a fuller and more emotional vocal presentation.

The treble range of the Dunu Falcon-C sounds detailed and airy same as the Fiio F9 Pro. The Dunu Flacon-C has the upper hand for treble extension, while the F9 Pro sounds smoother and has better control, especially in the upper treble range where the Falcon-C has some problems with instrument like cymbals and violins. The Fiio F9 Pro sounds also a bit hot compared to the Dunu Falcon-C.

The Dunu Falcon-C has a very expansive soundstage which is wider and deeper than those of the Fiio F9 Pro. But the problem is that this presentation sounds a bit unnatural especially with live recordings like acoustic, jazz, blues etc. genres, where the F9 Pro has a more organic and natural presentation.


Vs. iBasso IT01:

The Fiio F9 Pro and the iBasso IT01 are pretty good in the bass department. But there is some difference; the Fiio F9 Pro sounds more energetic, while the iBasso IT01 has a more dynamic bass presentation. The iBasso IT01 is a bit faster and has, while the F9 Pro has the upper hand for control. The bass texture on both devices is good but the IT01 has slightly more bass body. Both IEM’s sharing nearly the same level of bass resolution and there is no clear winner.

The Fiio F9 Pro sounds bit warmer than iBasso IT01, with the same V shaped tuning, which results to a distant midrange presentation. The midrange characteristic of the F9 Pro gives it additional air, while the IT01 sounds more intimate. The iBasso IT01 sounds also more transparent in the midrange department with good dynamics, while the F9 Pro has a more energetic presentation.

The vocal presentation of the IT01 tastes better with male vocals, while the Fiio F9 Pro sounded great with female vocals. The upper midrange of the IT01 has slightly more presence and sounds crisp, while the F9 Pro sounds more balanced and controlled.

Both have a well defined treble range with a nice amount of sparkle. The treble range of the Fiio F9 Pro sounds a bit hot, compared to the IT01 which feels more vivid and energetic. The iBasso IT01 has a good amount of detail retrieval, which can be compared with those of the F9 Pro.

When it comes to the soundstage both are performing well. But there is a difference in orientation; the IT01 has the wider soundstage, while the Fiio F9 Pro has more depth in presentation.


Both the TFZ Tequila1 and the Fiio F9 Pro have a V-shaped sound signature, while the F9 Pro has more balanced tuning.

The TFZ Tequila1 has more sub-bass impact which reaches also to a lower register, while the F9 pro sound more controlled in this department. The Fiio F9 Pro has the upper hand for bass quality and speed, which sounds more mature and with additional extension, compared to the energetic presentation of the Tequila1. The Fiio F9 Pro has also the smoother bass texture then Tequila1.

The midrange of the TFZ Tequila1 sounds crisp and nice textured, while the Fiio F9 Pro sounds more natural and engaging. The detail level is of the Fiio F9 Pro is slightly higher, which has also additional transparency. The vocal presentation of the TFZ Tequila1 is a bit more forward especially with female vocals, while the Fiio F9 Pro sounds more distant and natural.

The upper midrange of the TFZ Tequila1 is more prominent then those of the F9 Pro which gives the sound a vivid presentation. But the Tequila1 has some control issues with instruments like violins, pianos etc. where the Fiio F9 Pro does a better job.

The treble range of the TFZ Tequila1 is brighter, than those of the F9 Pro. The Fiio F9 sound more balanced and has the more controlled presentation. After all, the TFZ Tequila1 performs very well for a dynamic driver IEM and the treble speed of both IEM’s is nearly identical and there is no clearly winner. Both the TFZ Tequila1 and the Fiio F9 Pro have a nicely textured top end, with good clarity.

The upper treble range of the TFZ Tequila1 sounds a bit aggressive compared to the softer presentation of the F9 Pro, but there is no unnecessary harshness. The upper treble extension of the TFZ Tequial1 is better, while the F9 Pro has the better resolution.

The difference for soundstage performance is very low, but the Fiio F9 Pro has the overall wider and deeper soundstage presentation. The placement and imaging of instruments and vocals is slightly better with the Fiio F9 Pro.



Fiio did a great job by making such a good product for an affordable price. The Fiio F9 Pro sounds great out of the box with its quite detailed and balanced sound signature, has great ergonomic and a stylish appearance packed in a box with lots of accessories. Well done!


Summary (plus and minus):

  • + Nice balanced sound signature
  • + Good amount of detail
  • + Great build quality and ergonomics
  • + Lots of accessories (2 x cable, 2x case, etc.)


  • – The treble sounds a bit hot


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