FiiO FA9 Review





For the nit-picker and nerdy ones here, I’m giving the specs and technical sheets. For all the other, you can just go to the next page to see how the FiiO FA9 performs.

Six Knowles drivers 

Slowly, but surely, FiiO is getting higher and higher in the game.

The FiiO FA9 gets no less than six drivers, all provided by Knowles. The two makers tightly worked together, to come up with a new reference labeled “EJ-33877”. On paper, this new driver is supposed to offer excellent mid-frequency performance, with – quote – hauntingly realistic vocals.


To sum it up you get:

  • High/ultra-high frequencies: a set of SWFK-31736 “that blends extreme resolution with rich sound”, or so it seems.
  • Mid frequencies: the new EJ33877, co-developed with Knowles to attain new heights in terms of vocals
  • Low frequencies: HODVTEC-31618, a big driver with a dual-woofer that produce “dynamic and authoritative bass

So that’s the promise, and we’ll see if we can feel the difference. Or not.

Four-way crossover + Ultra-long tube

Surprisingly, FiiO didn’t go for a classic six drivers/three-way crossover. 

The FiiO FA9 has been given a four-way crossover that blends the lows, mids, highs, and ultra-high frequencies. These highs/ultra-highs separation is becoming a true trend, but sometimes the improvement isn’t obvious, or worse. 


FiiO advertises “dynamic bass, crystal clear yet lush vocals, and extremely detailed yet pleasant treble”. Thankfully, the brand already displayed nice successes previously, so I am pretty hopeful.

Last but not least, we have to talk about that “ultra-long tube”. I know some people may say that size doesn’t matter, but sorry for you guys, it really matters. The 80.6mm tube, which can be seen to the naked eye, acts as a passive low-pass filter. Thanks to that, the mids and highs blend seamlessly to give a more natural sound, with “smooth mid-bass” and “enhanced bass textures”.

Again, this is one of the most concrete proofs of what 3D-printing can offer us, to get a better sound, at the same cost. It’s quirky yes, but it’s also damn impressive.


Sound adjustment switches

Thanks to the various switches, the nominal impedance varies between 16 and 32 ohms, and sensitivity can reach 110/113dB. Good values that make the FiiO FA9 easy to drive, but also prone to catch any hisses and noises from your source.

Regarding the switches, here is a quick recap of what each of them does:

  • S1 on: lower impedance and higher sensitivity. Easier to drive.
  • S1 off: higher impedance and lower sensitivity. Less noise from your source (like an IEMatch from iFi audio
  • S2 on: treble boost. If you like your highs… highers
  • S2 off: treble normal. A more balanced sound, and more pleasant too (in my opinion)
  • S3 on: reduced bass and increase mids. A slight bump if you want to put the emphasis on voices
  • S3 off: increased bass and reduced mids. The default choice

A lot of choice and the brands gives you a few presets to match your tastes (standard / strong-bass / pop / crisp highs / etc…)

Let’s check the specs one last time, and get to what’s really important: the sound performances.


Full specs

    • Type : IEM
    • Style : Balanced armatures
    • Drivers : 2x Knowles (Mid) – 2x Knowles (Low) – 1x Knowles (High)
    • Socket : MMCX 
    • Cable : 5N Silver-Plated Copper 
    • Shell : Medical grade resin
    • Frequency Response: 15Hz – 40KHz
    • Impedance: 16 – 32 ohms
    • Sensitivity: 110 – 113 dB
    • Sound Isolation (up to): 30 dB
    • Cable length: 120 cm
    • Price: $499

The article continues on Page Four, after the click here


A nerdy guy with a passion for audio and gadgets, he likes to combine his DAC and his swiss knife. Even after more than 10 years of experience, Nanotechnos still collects all gear he gets, even his first MPMAN MP3 player. He likes spreadsheets, technical specs and all this amazing(ly boring) numbers. But most of all, he loves music: electro, classical, dubstep, Debussy : the daily playlist.

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