Review: FiiO F9 Pro – Optimus Prime

FiiO F9 Pro
Disclaimer: The FiiO F9 Pro was delivered to me directly from FiiO as they're one of our site advertisers. The price seems to be 139$ for now, 40$ more than for the standard F9. 


When I reviewed the FiiO F9, I was impressed by the sound quality and especially the build & design for 99$. FiiO certainly knows how to make bang for buck products as we know them for a long time now. But they also want to step up to the next level and quickly improve with each product they launch. As a result, the FiiO F9 Pro was born.

Just as I thought that the F9 could’ve been better in some ways, there came the FiiO F9 Pro. Some people don’t like the short cycles in terms of product releases, but seeing a company pushing for better is not necessarily a bad thing after all. And there we have the F9 Pro, saying “gently step aside” to the basic F9 and taking the spotlight.


There’s really not much for me to add in terms of “not sound” parts for the F9 Pro. There are some slight changes but at the end of the day they don’t impact the user experience significantly. While saying that, these small changes are very nice from FiiO nevertheless.

The female MMCX connectors have a slightly better angle for a more comfortable fit. There are easy to see L and R markings on the earpieces, and the cables also have blue and red color finish on the connectors. These small things create a better user experience overall, and add that “pro” touch to the earphones. Cables are also finished with right angled jacks this time. That’s also a more compact solution compared to straight jacks, at least in my opinion.

I’ve talked about all those things in my video below. Check it out to see the F9, F9 Pro and FH1, and of course their design differences. (The video had some focusing problems unfortunately, so sorry in advance. I’ll definitely solve that for the next ones)

For content, the F9 Pro has a secondary zipped case other than the weatherproof case provided and this is a nice addition. Sometimes it’s really handy to have a smaller, pocketable case to carry the IEMs in your pocket. Another addition is that foam tips are provided, and this  is really nice if you like foams like me, and I think the F9 Pro blends very well with them.

Other than those things, build quality, fit and design is all the same with the F9. The color of this one tough is a lighter gray. It’s the only color option for the Pro model and I personally like it. In fact, I think it looks even better than the F9 with a titanium-like appearance. I saw things about MMCX connectors failing at some point or a certain angle, but it was all OK in my case. Still, one should not overlook this issue. You can search on the web and look for the complaints.

In conclusion, the F9 Pro is not only better in sound, it also offers a slightly better user experience. If you would like to have more insight about this part, you can check out the original F9 Review as well. Let’s jump to the sound right away.

FiiO F9 Pro

FiiO F9 Pro


The difference between the F9 and the FiiO F9 Pro lies in the Balanced Armature drivers. FiiO managed to get the Knowles BA drivers and put them inside the Pro. I was a little skeptical about whether these drivers would make a big difference or not but in the end, it actually turned out to be a bigger difference than how I imagined it. My only expectation was the disappearance of that peak on upper mids/lower treble region; meaning the IEMs would exhibit a more controlled sound performance. But it’s definitely more than just that and I will explain those points shortly.

The FiiO F9 Pro presents a very clear sound like the standard version, but this time with more control and cohesiveness on the whole spectrum. I personally would skip the F9 and pay extra for the F9 Pro without hesitation, just for that reason. With that improvement, this I think has become even more “bang for your buck” now.

I tested the F9 Pro with the Sony WM1A and HiBy R6 DAPs.


On paper we should have the same dynamic bass driver from the standard F9 here. And precisely, the bass presentation does not contain a big difference when compared side by side. I will describe the lows of the F9 Pro right from the start, just in case you haven’t read the F9 Review beforehand.

The F9 Pro has a good slam and punch in its lows, but not overly so. It has a good amount of bass when needed, and gives you those sweet midbass tones when they’re present in the recording. The bass feels very natural as it’s a hybrid IEM with a dynamic driver, so this trait helps to have an airy sound overall. The midbass is a little more gripping compared to the subbass area, therefore I can’t say this IEM can reach down very deep. While saying that, I don’t think midbass compresses the sound stage or stereo image in any way. As I said, this is a dynamic driver, so midbass does not create that kind of a problem, like BA drivers do (when they have a big midbass focus).

Source also plays a factor here, as some DAPs give you a great bass control, and some don’t. In this case, the WM1A Walkman is very good in this regard. Midbass is under control at all times and again thanks to the dynamic driver, you don’t get a congested sound. Layering is not that great but that is not unexpected, since we are used to seeing great layering on IEMs which costs around 7 times more.

FiiO F9 Pro

FiiO F9 Pro

I think maybe FiiO can get a better response out of this driver with more precise tuning, although I personally enjoy the bass as it is. Like the F9, this is a natural and satisfying bass response, especially for the price.

Still, the F9 Pro’s bass feels a little bit fuller and more coherent compared to the original, thanks to the better mid/treble performance of the new Knowles BA drivers. With a more balanced and natural sound overall, the bass driver can show itself more with its performance and succession. As a result, the sound now is more connected across the spectrum.

Continue to the PAGE 2, where you can find more about the sound.

4.2/5 - (88 votes)

A keen audiophile and hobby photographer, Berkhan is after absolute perfection. Whether it is a full-frame camera or a custom in-ear, his standpoint persists. He tries to keep his photography enthusiasm at the same level as audio. Sometimes photography wins, sometimes his love for music takes over and he puts that camera aside. Simplistic expressions of sound in his reviews are the way to go for him. He enjoys a fine single malt along with his favourite Jazz recordings.


  • Reply February 13, 2018


    Thanks Berkham for your review. How do they sing with HiBy? Good matching? I have F9 Pro with Fiio X5 III and I am not particularly impressed. Would you swap the player?

  • Reply February 14, 2018


    Thank you too.

    Yes, I would swap the player. F9 Pro and Hiby pair very nice from the BAL output.

  • Reply February 14, 2018


    Good! Will consider highly your recommendation:)

  • Reply March 24, 2018


    I’m testing Shure SE 215 and FiiO F9 Pro. I can tell that bass is much better and deeper in Shure.
    Treble is different in both, Shure is well balanced. In FiiO treble is too intensive, not very natural however it’s a good quality.

  • Reply April 5, 2018


    Could you tell me if I have a good experience using this F9 Pro with a smartphone xiaomi (with internal dedicated dac) or they must be used with a specific DAP to reach a good result? At the same is different in terms of quality if i buy the F9 normal instead the Pro?

    • Reply April 6, 2018


      You should get the Pro model as it sounds much better. As for the smartphone, all devices have a dedicated DAC but that doesn’t mean anything. A phone will never sound on a level a good DAP does.

  • Reply April 8, 2018


    Sorry i am new to headphones and i want to get a pair of iems.I have about a budget of 250 usd.How should i spent the money worth?(sry for the bad english)

    • Reply April 9, 2018


      How will you use it? What musical genres? What source?

  • Reply August 31, 2018

    dhannjay sah

    very nice this blog

  • Reply August 31, 2018


    Thanks for the appreciation!

  • Reply September 12, 2018

    Sheridan Kamal

    May i know what type of cable that Fiio used for the balanced jack, is it necessary to change the cable to further improve the sound? Thanks.

    • Reply September 14, 2018


      “The 2.5mm balanced cable is made of silver-plated copper wire, which ensures a balanced sound signature and a high level of detail retrieval. Of course, due to its balanced nature, the left and right channel wires are separated so that there is significantly greater channel separation – leading to a richer, more detailed musical experience.”

  • Reply October 5, 2018


    Which is better between F9 PRO or Brainwavz B400?

    • Reply October 9, 2018


      I’ve never heard the B400.

  • Reply January 4, 2019


    How would you rate these against the Simgot EN700 Pro? Thanks.

    • Reply January 9, 2019


      I’ve never heard the EN700.

  • Reply February 25, 2019

    Rob Schschtet

    Comparing the 1 More Quad and the Fiio Pro 9, which one would you assess is better for classical music listening and why? And are there others in this price range even more suitable for classical
    Music? Thanks!

  • Reply June 25, 2019


    Does F9 Pro match with Shanling M0?

  • Reply August 10, 2019


    Hi Berkhan! Quite a detailed blog, many thanks for that.

    I have been inching towards ‘purer’ music while not splurging. I am looking to upgrade from Symphonized NRG 3.0 (~ $25, not so famous apparently, but bang for buck). I’ve been eyeing F9 Pro. I will be pairing it with Fiio MK3 (again, the starting baseline for Hi-Res DAC).

    Though it might appear counter-intuitive for this article, but would there also be other good earphones in this range that I could run my eyes over. I am looking to spend 5x vs. my old earphones, and plan to the make the best out of it 🙂

    Thanks in advance for the response.

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