FiiO FA9: balanced armature driver IEMs with adjustable sound signature


Mis à jour le 1 March 2021.

Today we are reviewing the FiiO FA9 in-ear monitors, the latest addition to the Chinese manufacturer’s FA line. The FiiO FA9 IEMs, which are marketed at €549, feature 6 balanced armature drivers and switches to adjust their sound signature. Considering the FH7’s outstanding performance, we were very much looking forward to trying these new in-ear monitors. After having achieved unanimous approval with its hybrid model, will the brand manage to repeat its feat?

The finish of the FiiO FA9 is reminiscent of a diamond’s facets. A design element that can be appealing but not very discreet.

FiiO FA9: the brand

We had the opportunity to talk about the history of the Chinese brand through several reviews, such as those of the FiiO M11, FiiO M11 Pro and FiiO M15 DAPs, and the test of the FiiO FH7 IEMs.

While FiiO first and foremost made a name for itself in the field of digital audio players and headphone amplifiers since its beginnings in 2007, the brand has gradually made a name for itself in the world of in-ear monitors, to the point of being able to compete with well known manufacturers of high-end IEMs. While the FiiO F5 and F9 in-ear monitors started paving the way for the brand, the FiiO FH5 hybrid earphones have kicked the door open. Combining a dynamic nano-composite polymer membrane driver dedicated to the low frequencies, a Knowles ED30262 balanced armature driver for the midrange, and a Knowles TWFK-31082 dual balanced armature transducer for the highs, these IMEs marketed at €279 quickly became the benchmark in their class for performance and design quality. 

The FiiO FH5 Hybrid Headphones combine a dedicated 10mm dynamic driver used to deliver low frequencies with two Knowles balanced armature transducers for the midrange and highs.

FiiO continued to expand its catalog with the FiiO FA7 balanced armature driver IEMs, the FiiO FH7 hybrid models featuring five drivers per earpiece and offering the possibility to mechanically adjust the sound signature. Thanks to an interchangeable cannula system, the sound of the FiiO FH7 earphones can be slightly adjusted to emphasize a certain range of frequencies. Without drastically changing the listening experience, this system allows you to highlight a particular frequency range in order to adapt the headphones to your preferred tastes and styles. 

The FiiO FA7 IEMs feature 4 balanced armature drivers developed in collaboration with Knowles.

FiiO’s range of iems continued to expand in 2020, with the introduction of the FiiO FD1 loaded with 10mm beryllium-covered dynamic drivers, the FiiO EM5 featuring a design that takes the classic esthetics of the earphones of the 80s and 90s and combines it with cutting-edge technologies, and the FiiO FA9, which we are reviewing today.

FiiO FA9: packaging and accessories

FiiO has accustomed us to a certain level of quality and choice when it comes to presentation and accessories and the FA9 is no exception. We found the same selection of tips, tools and carrying pouches as with the FiiO FH7 in-ear monitors, i.e.:

  • two pairs of memory foam tips (size M)
  • two pairs of balanced silicone tips (L and S)
  • three pairs of SpinFit silicone tips (L, M, and S)
  • a pair of bi-flange silicone tips (M)
  • three pairs of silicone bass tips (L, M and S)
  • three pairs of silicone voice tips (L, M and S)
  • a carrying pouch
  • a transport case
  • a cleaning brush
  • a magnetic cable clamp 
The FiiO FA9 IEMs come with a wide selection of ear tips, a carrying pouch, a protective case, a cleaning brush and a magnetic cable clip.

This wide selection of eartips is a crucial element in ensuring perfect ergonomics between the ear canal and each earphone. As with all in-ear earphones, choosing the right eartips is crucial to take full advantage of the FiiO FA9’s potential, but also to ensure long, fatigue-free listening sessions.

As we observed during our test of the FiiO FH7 earphones, the rigid carrying pouch is well-made and effectively protects the earphones while keeping the cable tightly coiled when not in use. The fabric pouch is smaller and can be easily slid into a jeans pocket for example. 

FiiO FA9: design and fit

Once again, FiiO has shown great expertise when it comes to the design of its in-ear monitors. While some models of earphones, especially the metal ones, can be heavy, tiring during long listening sessions or offer perfectible isolation, none of these flaws plague the FA9. Like the FH7 before them, these in-ear monitors are quite simply very comfortable to wear. Once the appropriate tips have been chosen, placing the earphones in the ear canal is extremely easy. All that’s left to do is to let yourself be carried away by the music for hours on end. At no point did we feel any sign of fatigue, even during listening sessions of 8 hours or more, with occasional breaks, of course. The FiiO FA9 In-Ear Monitors may well be the most comfortable in-ear earphones we have had the opportunity to test to date. The shape of the shell sits perfectly inside the ear and the earbuds’ light weight combined with their soft and balanced sound signature make them perfect partners for long trips and for music lovers looking for IEMs that allow them to enjoy music all day long. 

The ergonomic shape of the FiiO FA9 in-ear earphones allows them to rest perfectly in the conch of the ear and thus offer perfect comfort.

Esthetically speaking, the FiiO FA9 IEMs do not go unnoticed with their diamond-cut faceplate. We would have liked a slightly more understated finish, but this is not really a distinctive feature of the FiiO FA and FH series. Like the FA7 in-ear monitors, the shell of the FiiO FA9 is designed based on a DLP printing pattern. This technology allows for the production of resin shells with a very high degree of precision in order to maximize the shell’s internal acoustic space. The drivers are even visible through the transparent part facing the ear. While the metal shells found on models designed by Campfire Audio or SPEAR Labs give an impression of rock-solid solidity, these resin earphones do not seem fragile or cheaply made. 

The FiiO FA9 and FH7 IEMs are both light and robust.

The sound isolation of the FiiO FA9 is flawless. While we were impressed by the level of immersion offered by the FH7, the Chinese brand outdid itself with this new model. Nothing goes in and nothing comes out, so you’ll have to pay attention to your surroundings if you use these IEMs while walking around town.  

FiiO FA9: monocrystalline silver-plated copper cable

The FiiO FA9 in-ear monitors come with a FiiO LC-3.5B cable, an audiophile design made of monocrystalline silver-plated copper conductors. The earbud ends are fitted with MMCX connectors and the source end is a 3.5mm mini-jack connector. The contacts are gold-plated and the transparent sheath is reinforced with a second, stiffer layer at the ear to make it easier to hold each earphone in place. As soon as you get the cable out of the box, there is  no doubt that it is robust and well-designed. The MMCX connectors are solid and the braided structure of the conductors avoids knots but also reinforces the cable.

There is no doubt about the quality of the FiiO FA9s’ cable from the very first touch.

FiiO FA9:  balanced armature drivers

The FiiO FA9 IEMs adopt a 4-way design and feature 6 Knowles balanced armature drivers: 2 for the lows, 2 for midrange and 2 for the highs. Note that the two treble drivers are each in charge of reproducing a different frequency range, one higher than the other. Knowles is known for its expertise in the design of this type of driver, particularly for medical hearing aids. Ensuring a clear and natural sound reproduction is the company’s specialty as it is absolutely essential for hearing aids. The exclusive use of balanced armature drivers is a distinguishing feature of the FiiO FA range, which differs from the FH range whose models adopt a hybrid design, i.e. combining a dynamic driver and balanced armature driver. 

The drivers in charge of the delivering frequencies are SWFK-31376 models designed to offer rich sound and a very high level of detail. The EJ-33877 midrange driver was developed by FiiO and Knowles to ensure powerful midrange and accurate voice reproduction. Finally, the lows are delivered by the HODVTEC-31618 driver tuned for tight and precise lows. To ensure optimal articulation of the frequency ranges, the transducers are associated with a 80.6 mm tube acting as a low-pass filter. This structure filters out unwanted mid and high frequencies, ensuring that the frequency response is as even as possible for a smooth and balanced reproduction.

The internal tube structure of the FiiO FA9 IEMs is designed to filter frequencies in order to even out the frequency response as much as possible.

The exclusive use of balanced armature drivers in a 4-channel configuration is designed to ensure even, neutral sound and to extract as much detail as possible across the entire sound spectrum without putting an emphasis on any particular frequency range. With a frequency response ranging from 15Hz to 40kHz and a sensitivity rating of 110 to 113dB for 1mW of power, the FiiO FA9 IEMS are Hi-Res Audio certified and can be easily powered by any source. Let’s face it, the FiiO FA9s are not designed to deliver a downpour of lows and are primarily intended for people looking for accuracy and balance. 

The transparent resin shell of the FiiO FA9 in-ear monitors reveals their internal structure.

FiiO FA9: adjustable sound signature

The main novelty brought by the FiiO FA9 IEMs is the presence of selectors allowing you to electronically adjust the sound signature. While the FiiO FH7 in-ear earphones had already paved the way for a design that allows the user to slightly modify the restitution by changing the filter attached to the earphone cannula, the three selectors of the FA9s offer 8 different combinations (4 high impedance and 4 low impedance sound signatures). 

The selectors on the back of the FiiO FA9s allow you to slightly adjust their sound signature and change their impedance.

Selector 1 activated: low impedance and high sensitivity, allowing the FA9s to be powered easily.

Selector 1 off: high impedance for clearer, more natural sound. The sound is a bit darker and the noise level is even lower.

Selector 2 on: emphasizes high frequencies for a brighter sound.

Selector 2 off: standard amount of treble for a more balanced listening experience.

Selector 3 on: bass reduction and midrange emphasis, recommended for vocals and instrumental music.

Selector 3 off: enhanced bass and reduced midrange, recommended for classical and orchestral music.

The FiiO FA9’s response curve adjustment allows you to emphasize a range of frequencies or adapt the sound signature to a particular style. The switches located on the back of the shells allow you to slightly adjust the IEMs sound signature and change their impedance.

FiiO FA9: specs


  • High frequencies: 2 x SWFK-31736 balanced armature drivers
  • Medium frequency: 2 x EJ-33877 balanced armature drivers
  • Low frequencies: 2 x HODVTEC-31618 balanced armature drivers
  • Independent acoustic tubes (bass, midrange, treble)


  • Frequency response: 15Hz – 40kHz
  • Impedance: 16 to 32 ohms
  • Sensitivity: 110 to 113dB SPL @ 1mW
  • Max. permissible power Max.: 100mW


  • Monocrystalline silver-plated copper conductors with transparent sheathing
  • Gold plated MMCX connectors
  • 3.5mm angled mini-jack connector with gold-plated contacts

FiiO FA9: testing conditions

We used the FiiO FA9 IEMs with a Chord Mojo DAC connected to a computer via an Audioquest Cinnamon USB cable when sitting at a desk. For listening on the go, we used a FiiO M11 Pro portable music player and an Android smartphone. The files stored on the hard drive and on the player were in mp3 320 kbps, wav, FLAC and DSD formats. We also listened to albums in CD quality as well as Hi-Res (24-bit / 96kHz and 24-bit / 192kHz) via Qobuz thanks to our Sublime+ subscription. The sound signature of the headphones was set to standard at first (selectors 1 and 3 on, selector 2 off), then to enhanced bass (selector 1 on, selectors 2 and 3 off). 

The pairing of the Chord Mojo DAC and the FiiO FA9 IEMs offers a detailed, neutral and precise sound.

FiiO FA9: listening impressions

Bad Moon Rising, Creedence Clearwater Revival (Qobuz 24/192): The Complete Studio Albums of Creedence Clearwater Revival in 24-bit, 192kHz on Qobuz has become a regular feature in our IEMs reviews. As expected, the FiiO FA9s provided a great amount of clarity. The instruments were very detailed, the sound stage was wide and well layered. The high frequencies were never aggressive despite the absence of a dynamic driver. Once we adjusted the sound signature to emphasize the low frequencies, there was a little more substance in the lower end of the spectrum, without transforming these in-ear monitors into a completely different animal. The vocals were delivered with a stunning and natural sounding reverb. The FiiO FA9s proved to be very good with Hi-Res files.

Thriller, Michael Jackson (Qobuz 24/96): The meticulous production of this legendary album allowed the FiiO FA9s to show their true nature. The sound was accurate and all the instruments were placed very accurately without any overlapping effects. The stereo effect was flawless, the percussions gave rhythm to the song and we heard details that we never noticed before. The only drawback was the neutral and analytical behavior of the FA9s. This resulted in slightly underwhelming lows, which can be a bit frustrating with this type of music. Without being cold, these in-ear monitors simply don’t have the fervor of hybrid models. However, it should be noted that listening to the same track with the FiiO M11 Pro DAP produced better results with a more pronounced low end. Fans of round, rumbling bass will therefore be more inclined to go for this combination than for the Chord Mojo DAC. However, this track allowed the FA9s to show what they are capable of when it comes to vocals, and what a voice it is! During the spoken words at the end of the song, the Knowles balanced armature transducers do a great job at bringing the late great Vincent Price to life. A shiver ran down our spine as we listened to the rich and warm voice of the actor. The association with the keyboards in the background gave this iconic song the grand scale it deserves.

Listening to Michael Jackson’s Thriller was more pleasant with the FiiO M11 Pro than with the Chord Mojo.

Halloween Theme, John Carpenter (Qobuz 24/44): This 2018 version of the original theme composed in 1978 has been updated by Big John himself. With a punchier rhythm and fuller bass, this new interpretation of the classic also became instantly more enticing once the FiiO FA9 IEMs were paired with the M11 Pro. The lows were tight and responsive, and all registers were perfectly articulated which provided a consistent and even sound. John Carpenter’s writing style, which mainly consists of sound layers added on top of each other, is ideal for highlighting the meticulous restitution of the FiiO FA9s, which never became muddled or lost track of the music. These IEMs remain in control from start to finish and those who are looking for a faithful and precise sound reproduction will be won over.

Flashback, Hangman’s Chair (WAV, PCM 44.1 kHz, 16-bit): We listened to this track from the Parisian quartet exclusively on the M11 Pro DAP. The heavy guitars were reproduced with great clarity and energy despite them being downtuned. The remarkably clean lows of the FiiO FA9 shined a new light on this track. These IEMs brought forth details such as cymbal and hi-hat accents on drums, especially during the verse. Modulation guitar effects and vocals were also reproduced in an extremely detailed and natural way. Once again, we immensely enjoyed the precise and detailed sound signature of the FA9s.

Dreams, Fleetwood Mac (DSD): An ideal song to end our review. Stevie Nicks’ voice was detailed, crystal clear and simply enchanting. The bass guitar and kick drum were crisp and brought rhythm to the song while the backing vocals and guitars filled the rest of the sound stage. The hi-hat and snare drum sounded strikingly realistic, the restitution was balanced and well defined. The FiiO FA9s paired with the M11 Pro provided a natural and immersive listening experience, especially with high-resolution files. It is quite simply a perfect match.

Listening to the Fleetwood Mac’s album Rumors album in DSD with the FiiO FA9 IEMs connected to the FiiO M11 Pro DAP was a real treat.

FiiO FA9: compared to…

Shanling ME700: Shanling and FiiO both understood that it was essential to offer a wide choice of eartips to guarantee optimal performance thanks to a perfect ear canal/IEM coupling. However, the FiiO FA9 are a bit more comfortable. They also have the upper hand when it comes to versatility thanks to their adjustable sound signature. Overall, the FiiO FA9 is characterized by a more neutral sound signature and a more accurate reproduction, while the Shanling earphones benefit from more substantial lows thanks to their hybrid design. 

Shure SE535: The Shure SE535 in-ear monitors have just found a strong competitor when it comes to comfort and fit. Despite their rather neutral signature the FiiO FA9s remain less analytical and a lot more musical than Shure IEMs, whose design is directly inherited from stage in-ear monitors. However, for professional use or for working out, the Shure IEMs are undeniably the best, especially with their Bluetooth adapter. 

FiiO FH7: It was no easy task to keep this comparison for the very end of the review. These two pairs of IEMs by FiiO are completely different beasts and are not meant to compete with each other, but rather to offer different options to IEM enthusiasts, just like Campfire Audio, whose in-ear monitors are all tuned to offer a different sound signature. We’ve gone back and forth between the two, sometimes preferring one and sometimes the other. The FH7s standout with their fun sound signature and rich and neat lows. The FA9s are more rigorous and matter of fact. They also definitely have the upper hand when it comes to sound isolation. Imagine two brothers: one serious and meticulous, the other playful and extroverted.

The FiiO FA9 and FH7 in-ear monitors are both great companions for the FiiO M11 Pro.

FiiO FA9: conclusion

Without being as analytical as in-ear monitors for professional musicians, the FiiO FA9s are well balanced and deliver a soft, neutral sound. FiiO’s signature sound tuning system is subtle and lets you adjust the sound just enough to be noticed. The midrange is rich, the highs are detailed and the lows remain precise and tight at all times. However, as we have noticed during our listening sessions, the latter can be a bit too shy with some sources. Far from being what some people call a “bass cannon”, the FiiO FA9 IEMs are primarily intended for folk music, orchestras, acoustic music or musical genres where vocals are the main focus. More modern music or tracks that are extremely rich in bass will greatly benefit from the association with a player equipped with an EQ function such as the FiiO M11 Pro. 

With their excellent isolation and natural sound signature, the FiiO FA9s allowed us to fully immerse ourselves in the music and the spirit of the season.

Once again, this is a complete success for FiiO who have released comfortable IEMs with a balanced and natural sound signature. The FiiO FA9 in-ear monitors have no issue competing with models seemingly above their category and one can imagine their potential when combined with a high-end cable such as the FiiO LC-RE MMCX.

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Amateur de disques vinyle et passionné d'obscurs sous-genres musicaux, mes préférences cinématographiques s'orientent vers les films d'horreur, des classiques Universal aux slashers et films fantastiques des années 80, ainsi que vers la période américaine d'Alfred Hitchcock. Côté matériel je privilégie une installation hi-fi épurée et sobre pour l'écoute de supports physiques et l'utilisation d'un ensemble DAC / écouteurs intra-auriculaires pour les plateformes de musique dématérialisée telles que Qobuz et Bandcamp.

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