This and That:
Plenty of accessories, good build quality.
Sound:
For listening, I only used low impedance sources, mainly the iBasso DX200 (AMP1 module).
Mainly the largest included white silicone tips were used for listening and all comparisons.
Tonality:
Quite interestingly, the included white silicone tips have got the least amount of upper treble elevation out of all included silicone tips. They also slightly lift the lower and middle treble (~ 3 to 6 kHz) though, which is not so good in case of the F9 Pro, however they make the upper treble the least sharp in comparison.
Covering the dynamic driver’s front cavity vent, which is true for pretty much all dynamic driver and hybrid in-ears, will increase bass quantity quite noticeably. Depending on your individual ear anatomy, this vent might be either free, fully blocked or somewhere in-between.
Interestingly enough, in my ears, this vent remains quite free, which is not often the case for my ear anatomy, so all of the following impressions are written with the front cavity vent remaining free (= least amount of bass).
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Bass is on the balanced side, with a rather modest lift of ca. 5 to 6 dB compared to an in-ear that is diffuse-field flat in the lows, such as my Etymotic ER-4S/the ER4SR. It starts rising around 800 Hz and reaches its climax around 200 Hz, and extends into the true sub-bass with almost no level drop, and certainly no roll-off. Due to the rather modest and balanced bass lift as well as its quite flat extension, don’t expect any real deep, visceral rumble though.
Yep, the F9 Pro is far from basshead levels and features a quite balanced bass presentation with the right balance between a little punch and evenness, and its lows also stay out of the midrange quite nicely.
The mids are definitely on the brighter, leaner side with a lift from 1 towards 3 kHz, something that gives them clarity and more presence in the mix and helps vocals to retain presence instead of appearing too distant, although the presentation is not exactly “in your face” either.
The problem with that is however that a midrange tuning like this, while quite appealing sometimes, isn't very natural, and undeniably a colouration - one that you may like or dislike; it's by the way rather popular among hybrid in-ears coming from Asian manufacturers, and is implemented to emphasis "air" and "clarity". Nonetheless the amount of leanness in the mids, while not as bad as the Fidue A85 that is a bit overdone (the F9 Pro still has a little bit of countervailing lower midrange body and is a little less elevated in the upper mids, and the balance between subtle warmth and clarity is overall better-made), might become a bit annoying over time and doesn’t always fit to the singer’s voice – I would say that it works sometimes, but sometimes the vocal timbre can already appear a bit too off to enjoy the sound.
Above that, there is another lift at 5 kHz, followed by a rather strong peak at 8 kHz and really good extension past 10 kHz.
Therefore the highs are quite undeniably on the bright side and the F9 Pro is an in-ear that was rather designed for treble lovers.
While sibilance and vocal sharpness are still not overly pronounced, the 5 kHz elevation adds some metallicness to the presentation while the 8 kHz lift tends to a bit of sharpness at times. This is probably still okay and tolerable for some people for a hybrid in-ear at this price point and nothing that cannot be fixed without some EQ tweaks, however a bit more evenness and probably a headroom-generating dip around 5 kHz would have been nicer for an overall more even and realistic treble presentation. It overall just feels “rougher” and “edgier” than comparably bright dynamic driver in-ears, giving the F9 Pro a rather “hard” and unforgiving sound in the highs, and I wish that FiiO went for a more natural midrange and treble tuning. The cheaper FiiO FH1, despite having much more bass in comparison, is an in-ear that I would personally always favour over the F9 Pro, as it is overall tuned much better in the mids and highs.
Resolution:
On the technical side, the F9 Pro is a quite convincing in-ear that sounds just like what you probably wish a hybrid in-ear to sound like at this price point – clean and crisp midrange and treble with good separation, together with a bass that has got somewhat more decay and less tightness compared to most Balanced Armature woofer implementations, while still sounding quite controlled, giving it a character that most people would refer to as “natural”.
Bass definition and control are good for the price and class, albeit not as fast and tight as the iBasso IT03 that is among the fastest and tightest hybrid in-ears when it comes to bass. It doesn’t sound muddy though and also doesn’t appear disconnected from the mids and highs, so coherency is quite good (while tuning coherency could be a bit higher in the highs).
With quick bass punches and attacks, lows tend to lose a little focus, which is common for implementations that are not extremely fast and tight, but always remain distinguishable.
Separation in the mids and highs is quite precise and speech intelligibility is also good.
Soundstage:
The F9 Pro neither disappoints nor really excels in this area – on the whole, its spatial presentation is rather average, with a somewhat wider than deep presentation while there is still noticeable front projection with surprisingly good layering that lets you discern far and close instruments as well as those in-between quite well.
Imaging is quite good too, and the portrayed “empty” space between instruments is pretty clean.
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In Comparison with other hybrid Triple-Driver In-Ears:
Fidue A73:
Bass level on both in-ears will ultimately depend on how much the inner vent is covered, but nonetheless the Fidue has got the warmer and fuller lower-end presentation with more warmth and body in the root/fundamental range and lower midrange.
The FiiO is a bit brighter, leaner sounding in the midrange, with the Fidue having a gentler clarity lift in the lower highs/upper mids, making it more appealing to a wider audience.
While the Fidue is already a bright in-ear in the upper highs, the FiiO’s upper treble peak is stronger and tends to more sharpness – the Fidue just has that 5 kHz dip that is necessary to generate the headroom for the peak whereas the FiiO is a bit over-energetic here.
Bass definition on the FiiO is ultimately a little higher, with the Fidue appearing a bit more layered and textured as a result of its somewhat softer, more body-focused presentation. Control is still quite comparable though.
The FiiO has got the more revealing character since it is brighter in the highs, but I’d also generally say that the FiiO is a little ahead when it comes to separation and precision in the mids and highs. Still not a large difference, but noticeable with faster and more complex music.
The Fidue has got the somewhat more open and slightly wider soundstage while imaging is comparably precise, however the FiiO has got a bit of an advantage in the end when it comes to the cleanness when portraying “empty” space between musicians and instruments.
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Subjectively, I personally prefer the Fidue’s tonal tuning that is somewhat less “aggressive” in the highs despite also being on the brighter side with an upper treble peak, while the FiiO offers a bit more precision and more features as well as accessories for roughly the same price.
1More E1001:
Even with fully open vents, the E1001 is bassier than the F9 Pro.
The E1001 has also got a somewhat clarity-oriented midrange tuning, but the F9 Pro is ultimately a bit leaner sounding overall. While the E1001 has got a dip in the middle highs around 5 kHz, the F9 Pro is a bit elevated in that area.
The E1001 peaks at a higher frequency in the upper highs, with comparable but ultimately still slightly quieter levels.
In the lows, the E1001 is (audibly) softer and looser, with inferior speed and control. Therefore it feels a bit disconnected from the rest, something I criticised quite a bit in my original review. Coherency is therefore superior on the F9 Pro that also sounds noticeably better separated and focussed with complex and fast tracks.
The 1More has got the wider soundstage that also sounds a bit more open, however separation is a bit cleaner on the FiiO that also has the more precise layering.
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Overall the E1001 is the easier to listen to and more mass-friendly in-ear with its u-to-w-shaped tonality, however when it comes to technical abilities and driver coherency, it ultimately loses audibly against the FiiO. Without EQ adjustments, I'd still pick the 1More over the FiiO if I really had to choose.
Conclusion:
Accessories and technical qualities are good, but when it comes to midrange and treble tuning, the FiiO F9 Pro is an in-ear that is clearly aimed towards treble lovers. Really, some more naturalness and less exaggeration would have made it an easier listen.