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FiiO F9 Pro Hybrid Triple Driver In-Ear Monitors Review

Back on the 2nd of November 2017, Porta-Fi was privileged to visit FiiO’s office and manufacturing facility in Guangzhou, China when we were in town to attend the Guangzhou HiFi Headphone & Digital Audio Expo 2017. This was when I first had an audition of the FiiO F9 Pro Hybrid Triple Driver (F9 Pro) In-Ear Monitors (IEM) which was slated to be announced and released during FiiO’s Autumn Launch Event at Expo on the 4th of November 2017 together with the FiiO FH1, Q5 and the FiiO Music App for iOS.

The event also marked a milestone to the working relationship between FiiO and Knowles with a trademark authorisation signing ceremony authorising the use of Knowles’s logos on the packaging of FiiO’s products featuring components from Knowles starting with the F9 Pro and the FH1.

FiiO F9 Pro

The F9 Pro is a pair of hybrid In-Ear Monitors comprising of 1 Dynamic Driver (DD) and 2 Balanced Armature (BA) drivers retaining the same 9.2mm DD as the one found on the F9 which is made of polyether ketone (PEK) polymer nanocomposite, replacing the original 2 BA drivers with Knowles’s dual BA TWFK-30017-000. Priced at USD 139.99, the F9 Pro is priced USD 40 more than the F9 and was the company’s highest priced IEM prior to the introduction of the FH5 earlier this month.

Build and Design

Weighing at about 3.76g per monitor, FiiO retained the organic and ergonomic design which was first used on the F9. Fits like a glove to the ear; the F9 Pro is not fatiguing and allows one to enjoy music for hours comfortably.

FiiO F9 Pro

In October 2017, two months after the release of the F9, FiiO announced adjustments to the F9 and F9 SE which include adding spiral lines to the end of the cable connecting to the MMCX connector, removal of MMCX spacer, adjustment of the angle between the shell and the connector to allow third-party cable compatibility as well as the addition of a strip of decorative seam at the joint to address the issue of different joint sizes on left and right monitors.

FiiO F9 Pro

All of which has been implemented in the design of the F9 Pro, with the addition of red and blue rings to the end of the cable connecting to the right and left MMCX connector respectively for easy identification. Meticulous details such as this coupled with the laser-etching of PRO logo on the monitors and the Y-split tells you how much FiiO has progressed as an earphone manufacturer.

FiiO F9 Pro

Spotting a smooth contour with no teething edges, the build is excellent and what you would expect from a manufacturer like FiiO. Finished in Titanium colour, the F9 Pro is encased in an Aluminium CNC shell with its inner layer specially lined with plastic to better secure the drivers and eliminate internal resonances. FiiO’s choice of colour provides the IEM with a finish that accentuates the ripple contours, differentiating it well from the red and black finish of the F9 and F9 SE.

Aligned with FiiO’s theme of “Infinity Sound” in 2017, the F9 Pro comes with two 1.2m detachable cables terminated with gold-plated MMCX connectors; a single-ended black TPE jacketed cable with in-line control, with tin-plated copper for the core, terminated with an L-shaped 3.5mm TRS jack and a balanced black TPE jacketed cable, with four carefully-woven 5N purity oxygen-free copper (OFC) core, terminated with an L-shaped 2.5 TRRS jack.

FiiO F9 Pro

Besides the cables, the F9 Pro is accessorised with a selection of 12 ear tips which include; three different kinds of silicone ear tips in small, medium and large size as well as 3 pairs of foam tips in a one-size-fits-all configuration. Also included is a waterproof carrying case, a water-resistant neoprene carrying pouch. It is certainly not hard to see that the company has made efforts to make the F9 Pro a better user experience which further illustrates FiiO’s maturity as an earphone manufacturer.

Sound Quality

When I first had an audition of the FiiO F9 Pro at FiiO’s office on the 2nd of November 2017, I was curious about how much difference changing the 2 BA drivers used by the F9 to Knowles’s dual BA TWFK-30017-000 would make and define the F9 Pro. It turns out that I was pleasantly surprised and confident that FiiO has a winner in its hands.

Clarity and cohesiveness across the spectrum define the F9 Pro and differentiates it from the F9.


As with any hybrid configuration, the low-end frequencies are managed by the dynamic driver which is the same 9.2mm polyether ketone (PEK) polymer nanocomposite used by the F9. The natural bass produced by dynamic drivers facilitates the airiness of the overall listening experience, a trait which for me is essential in the reproduction of any genre and thus my preference for single DD and hybrid IEMs.

The F9 Pro’s low-end is relatively dynamic with a good amount of punch and slam. It exhibits an engaging mid-bass with reasonable depth and decent sub-bass extensions which enables greater details to come through allowing the F9 Pro to sound fuller in a balanced and controlled manner while retaining linearity, clarity and coherence with the rest of the frequency spectrum.


The F9 Pro exhibits excellent tonality which is already evident during my first audition of the IEM. Its coherence from the lower to upper midrange without any harsh peaks is an exhibition of control asserting the qualities of the Knowles driver. Coupled with the decent bass presence, the lower midrange portrays transparency, neutrality with decent clarity.

While maintaining coherence with the low midrange, the upper midrange is slightly forward providing for a more lifelike and engaging experience with enhanced clarity and resolution. This translates into natural, accurately voiced vocals with great projection and clarity, especially that of the fairer sex.

The midrange on the F9 Pro is rich, exhibiting higher foreground and background resolutions contributing to its musicality.


The attribute of control extends into the highs, ensuring control over the higher frequencies resulting in the F9 Pro having a more linear treble without any harsh peaks. The lower-treble exhibits clarity with dynamic details where strings are crisp and full-bodied with a good degree of decay.

The treble linearity further extends itself into the mid and upper treble allowing for greater airiness and sound imaging with a bit of sparkle. Treble extensions are present and impressive considering the F9 Pro’s price positioning, enhancing resolution and sound separation.

The treble of the F9 Pro is one of clarity and high resolution; it is coherent with quality and impressive extensions.

Review Ratings
9.1 / 10 Reviewer
{{ reviewsOverall }} / 10 Users (0 votes)
- Excellent build quality
- Comfort
- Value for money
- Poor isolation

The F9 Pro is possibly the most impressive IEM I have heard at this price point.

Achieving maturity in build quality and making efforts towards a better user experience, FiiO has demonstrated how much it has progressed as an earphone manufacturer within a short span of time.

The impact the Knowles dual BA driver has made to the sound quality further justifies the USD 40 premium over the F9.

Sound Quality8
Build Quality9.5
Design & Usability9
Value for Money10
Associated Equipments
Product Specifications
  • Impedance: 28Ω
  • Driver configuration: Triple hybrid (1 DD + 2 BA)
  • Frequency response: 15 Hz ~ 40 kHz
  • Sensitivity: 106 dB/mW
  • Cable length: 120cm
  • Weight: 21g
  • Price: USD 139.99  (SGD 219)
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Goh Beng Yeow
Goh Beng Yeow
Goh Beng Yeow, the Founder / Editor at Porta-Fi™, is a recipient of the IT Youth Award in Singapore. Twice nominated for EY Entrepreneur of the Year Awards, Beng Yeow has previously founded startups such as PDALive.com, Coded Pixels Consultants and was a Tech writer for TODAY, a national daily newspaper under MediaCorp. Since 2017, he has been writing, editing and producing commentaries, interviews, news and reviews on Porta-Fi™. In 2019, Beng Yeow was appointed Advisor to LHDC™, the industry's latest low latency and high-definition Bluetooth audio codec.

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