Fiio F9 Pro Review – Pure Clarity

Sound –


Tonality –

With a more linear treble response, the F9 Pro forgoes the analytical v-shaped signature of the original in favour of a more balanced u-shaped tonality with more tasteful brightness. Bass is enhanced over neutral but rarely becomes the focus of the sound while mids are clear and well-present, especially with regards to upper mids. Treble is emphasized with a notable lower treble hump though the F9 Pro avoids becoming over-forward within the higher-frequencies as the original could. Considering Fiio’s asking price, this is a very nicely balanced take on a brighter signature and one that is well-compensated by tasteful bass enhancements. They are immediately more natural and balanced than the original model, not to mention, the vast majority of competitors sitting around the $100 mark.


Bass –

The F9 Pro’s low-end delivers relatively agile notes with nice punch and slam. Bass is skewed warm and its quantity is slightly lifted though never to the extent that balance and control are compromised. Interestingly, the Pro differs noticeably from the original F9 despite using the same dynamic driver. This is most likely a result of reduced treble colouration, with more restrained treble emphasis netting increased overall balance and subjectively greater perceived bass emphasis. So where the original F9 was mid-bass orientated and more reserved in its tuning, the more balanced Pro has perceptibly more bass depth and sub-bass impact if similar extension. Upper-bass is also elevated to a small degree, producing a slightly organic but otherwise uncoloured lower-midrange presentation.

By lowering the treble as opposed to boosting the Pro’s bass, the new F9 manages to sound appreciably fuller without compromising nuance, in fact, it’s quite the opposite. Due to greater linearity, bass has more density and body without sounding overly warm, thereby keeping bloat in check. Though sub-bass is still a little slow, this tuning does create more defined bass notes with reduced mid-bass focus enabling greater detail to shine through. As a result, though similar to its progenitor, the Pro represents a step up in quality with more accurate texture and tone. Through these alterations, the Pro sounds more natural and linear into the midrange frequencies in addition to sounding cleaner and more defined within the lower registers.


Mids –

With a slightly brighter signature, the F9 Pro focusses on clarity and energy over dynamics and body but it remains a remarkably accurate performer overall. The Pro is immediately more natural than its predecessor due to reduced treble colouration and relatively increased bass presence; they no longer require the adjustment period of the F9, simply sounding correct. Some clarity is compromised, but the F9 Pro produces a far more neutrally bodied and discerning presentation than before while remaining clear and immediate. Male vocals sit slightly behind, though the lower midrange is quite transparent and accurately bodied with bass spill being a non-issue. Lower midrange elements such as piano and guitar are full without becoming tubby producing defined and well-delineated notes. Though not an especially warm earphone, some tinges are present which grants the Pro with a slightly more organic lower midrange presentation.


Upper mids tell a similar story, higher elements are slightly forward with more clearly enhanced clarity, but vocals never encroach upon fatigue or stridence. Again, the Pro’s more linear treble tuning creates more accurately voiced vocals, alleviating the unnatural presentation of the original almost entirely. As a result, the Pro really excels with female vocals that are clear and sweet with great projection and resolution. The Pro also has a far smoother upper-midrange to lower-treble transition that greatly aids detailing and separation as the finer details are no longer overshadowed. Resultantly, the Pro not only retrieves more background detail, but foreground details are presented with greater realism and separation, creating a sound that is appreciably more nuanced and considerably more musical.


Treble –

The original F9 swung hard with its treble, some would say it was even a little ham-fisted in its approach. That said, it was still a well-detailed and resolving earphone that was mainly let down by its isolated lower-treble spike. The Pro isn’t much darker rather, treble is just slightly more restrained in emphasis and that emphasis itself extends over a larger range of frequencies. As a result, treble is more linear, lacking most of the peakiness of the original, and highs are more bodied and realistic if similarly forward in the mix. These improvements begin with the lower treble that retains the same aggressive detailing of the original with an extra layer of cleanliness and separation on top. Guitars are very crisp with great attack and resolution of micro-details, and cymbals, though still slightly thin, are well textured with pleasing decay.

The F9 Pro’s treble emphasis declines smoothly into a linearly extending middle and upper treble, granting the Pro great air and consistent instrument placement. Through this, the Pro also avoids sounding overly busy or crunchy within the higher frequencies when listening to complex tracks. Extension is very impressive considering Fiio’s asking price and a noticeable improvement over the original, contributing to heightened separation and micro detailing throughout. High-hats, in particular, are delivered with accurate shimmer and notes within the highest registers avoid truncation. Instruments are also presented with copious air and treble remains linear into the upper registers if with slightly less accentuation than lower treble elements. Treble has great resolution and clarity while remaining cohesive and the F9 Pro achieves its nuance not through exaggeration of a particular frequency zone, but through terrific quality and extension.


Soundstage, Imaging and Separation –

The F9 Pro produces a well-sized stage that reaches to the periphery of the head but very rarely extends beyond. They combine great width with nice depth to create a multi-faceted if not totally immersive presentation. Imaging is notably improved over the F9 as is separation on account of the Pro’s more balanced, extended sound. The Pro’s enhanced clarity and upper midrange/treble energy deliver directional cues with great accuracy and a strong centre image. The F9 Pro’s relatively uncoloured sound produces defined layers that weave a coherent and accurate presentation.


Drivability –


The F9 Pro retains the same 28-ohm impedance and 106dB sensitivity of the original making it similarly easy to drive. As with the F9, it isn’t overly sensitive to hiss, essentially silent from the balanced output of my X7 II w/AM3A in addition to my HTC U11. It delivers plenty of volume from portable sources with adequate sensitivity to compensate for louder environments. The Pro isn’t overly affected by output impedance but its resolving nature does enable it to benefit from a similarly resolving source. That said, the Pro’s more natural sound makes it notably less particular about source synergy than its predecessor; so where I preferred to run the F9 from my warmer Chord Mojo and Alien+, the more neutral tones of the X7 II provided the most transparent pairing with the Pro. Fiio are also pushing balanced connectivity with the F9 Pro, I noted similar changes with slightly more separation and space though again, this could be due to the fact that the balanced cable is notably enhanced over the regular 3.5mm remote cable.

Next Page: Comparisons & Verdict



Ryan Soo

Ryan Soo

Avid writer, passionate photographer and sleep-deprived medical student, Ryan has an ongoing desire to bring quality products to the regular reader.


9 Responses

  1. Can you compare them to rose mini 2? I was wondering which one has greater detail and better resolution, but I’m worried that F9 Pro will have too recessed mids for me.

  2. How does the F9 Pro compare to the Fiio FH1? I love techno and electronic music so I think the FH1 may be perfect for me especially since it costs half the price.

  3. Based on the comparison of the Kinera H3 to the Fiio F9 (non-Pro), and then the comparison of the F9 to the F9 Pro, I am assuming that while the F9 Pro is an overall improvement over the F9, if I’m currently happy with my H3’s I shouldn’t really feel the need to rush out and buy the F9 Pro’s?

  4. please make a comparison between these and altone 200.

    also considering altones price and same sound-wise character, is there a better iem in general???

    (also i found altones superb comparing them to fiio ex1ii using my fiio x3ii!!!)

    merry Xmas!!!

  5. Hi KH,

    The P1 and P2 are pretty similar, but the P2 is warmer with more bass extension and lower-midrange presence. It is a bit less refined than the P1 and treble isn’t as extended so it isn’t quite as comparable to the F9 Pro on a technical level, but both are tonally in the same ballpark. I provided more detailed comparison to the P2 in my regular F9 review, many of these comments can extend to the F9 Pro.


  6. How is F9 compare against Pinnacle P2? When I read the comparison, I feel like I am reading the comparison between P2 and P1 as well. How similar or different between F9 and P2.

    As usual, I enjoy reading your reviews. Please keep up the great work.

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