<ul> <li>Headphone type: Hybrid IEM</li> <li>Frequency response: 15Hz-40kHz</li> <li>Drive type: 1 dynamic + dual balanced armature drivers (Knowles)</li> <li>Impedance: 28Ω</li> <li>Sensitivity: 106dB/mW</li> <li>Cable design: Detachable with...

FiiO F9 Pro Hybrid Triple Driver IEM

    • Headphone type: Hybrid IEM
    • Frequency response: 15Hz-40kHz
    • Drive type: 1 dynamic + dual balanced armature drivers (Knowles)
    • Impedance: 28Ω
    • Sensitivity: 106dB/mW
    • Cable design: Detachable with standard MMCX connectors
    • Cables: (2) - 1.2m 2.5mm Balanced + 1.2m 3.5mm Single Ended
    • Jacks: 2.5mm TRRS right-angled gold-plated / 3.5mm right angled gold-plated
    • Weight: approx 21g
    • Casing: Anodised CNC aluminium alloy
HeadphoneBrnout and FiiO like this.

Recent Reviews

  1. SilverEars
    FiiO F9 Pro Review
    Written by SilverEars
    Published Jan 24, 2018
    Pros - price, build, fit, presentation, accessories, good sound articulation and clarity
    Cons - foam tip sizing, treble peak causing some sibilance
    Fiio F9 Pro is a dual BA, single dynamic, hybrid in-ear monitor with detachable cabling. It comes with two cables utilizing MMCX connectors, a 3.5mm cable with a microphone, and a 2.5mm balanced cable. Also comes with 4 different types of tips, foam, large bore diameter silicone, smaller bore diameter silicones. I find that the small diameter bore silicone tips drops mids and the highs, but does it in a veil sounding way which I wasn't so fond of. I was a bit bummed that all the foam tips were on the small size, and there wasn't one that would seal my ears. I know it's ok for foam to generally be on the larger size because you can compress it to fit your ear. Fortunately, large size, large diameter bore silicone tips fit my ear very well, and I found it to be the best sounding tips.

    I've unboxed Fiio products in the past, and they generally don't skimp on the packaging or accessories. The inclusion of balanced cable is a nice touch among all the accessories provide.

    The form-factor pretty much nails the ergonomics I look for. It's compact, and shaped to adhere to your ear shape with the cable going over the ears.

    Source pairings:

    Mojo: The upper mids is emphasized a bit too much. Upper bass is a bit lacking. Bass doesn't sound even, more sub-bass presence and with the treble sounds overly U shaped. Poor match.

    Opus #2: Much better match than the Mojo. Signature is more balanced than the Mojo. Also there is more bass presence. Lower treble is still emphasized, but not as much as the Mojo.

    AK240: I think AK240 is the best match for the F9 Pro. I think in general AK240 has most mid presence out of the 3 players I've tried(which was needed), and sounds good out of it. Also the 240 outputs the most articulate bass of the 3. Opus #2 in comparison, quality of bass isn't up the level of the AK240(and this is generally true of all the iems I've tried).

    On tracks with a bit of sibilant vocals, the sibilance is a bit over-emphasized. In general, the treble presence region has a bit of emphasis.

    If the sibilance can be suppressed, I think this iem would sound better than it does. I think the boost in this treble region cause tonality to sound toward metallic for certain tracks that have good amount of that frequency band presence. Reminds me of HD800 tuning except F9 Pro has sufficient bass in comparison. There isn't a lot of bass presence, but it's quite sufficient and sound like it does reach deep to the sub-region for tracks that outputs it. The bass sounds good in articulation without bloat(this is particularly the case out of AK240 out of all the three players), but not significant in quantity(it's the level of bass you find in neutral tunings).

    Playing around with EQ on the Opus #2, I discovered drop in 8khz reduces the sibilance a bit. The EQ on the #2 is a graphic equalizer, only 8khz was one of the limited options. So the treble peak is somewhere in that region. If you can EQ down the treble peak, I think the iem would sound neutral with a reference like signature.

    Due to it's tuning, the general sound signature is toward clarity. With the presence region emphasis, and mids to bass sounding neutral, it outputs much articulation without warmth emphasis.

    Overall a nicely built iem with good number of accessories. It's an iem to consider in the price range. Considering the price, it's a good value for what you are getting.
  2. HiFiChris
    FiiO F9 Pro - "Mrs Knowles"
    Written by HiFiChris
    Published Jan 20, 2018
    Pros - •value
    •balanced tonality
    •great technical performance for the price
    •really well-done blend of dynamic bass character and control
    •plenty great included accessories
    •build quality, ergonomics, design
    Cons - •treble somewhat on the hotter side
    •a bit more treble linearity would be desirable
    •mids probably a touch too much on the leaner side

    Originally posted in English on my mixed language English and German audio review website, the "Kopfhörer-Lounge", here comes my review of the FiiO F9 Pro hybrid triple-driver.


    FiiO have definitely come a long way since they started – and they turned into a large, influential and important audio company over the years.
    I have owned (and still do) several of FiiO’s products, and was among the first who purchased the first generation of the X3 digital audio player that, while it experienced some delays until it finally hit the market, probably introduced a new era of portable audio players, bringing a solid noise performance, low output impedance and good measurements down to a reasonable price.


    As time went by, FiiO’s line of digital audio players evolved more and more, and they eventually also introduced various in-ears, such as the hybrid triple-driver F9 that now gets a “Pro” version which basically differs from the regular one by using two different Balanced Armature drivers from the well-known manufacturer Knowles.

    How does it sound? Let’s find it out!

    Full disclosure: I was provided with a sample of the FiiO F9 Pro in-ears free of charge for the purpose of an, as always, unpaid, honest and unbiased review that reflects nothing but my own impressions and wasn’t given any directions/guidelines, no matter how it would turn out.

    Technical Specifications:

    MSRP before Taxes: $139.99
    Type: Hybrid In-Ear
    Drivers per Side: 3 (1x dynamic driver, 2x Balanced Armature (Knowles TWFK-30017-000))
    Frequency Response: 15 Hz – 40 kHz
    Impedance: 28 Ohms
    Sensitivity: 106 dB/mW
    Maximum Input Power: 100 mW

    About hybrid In-Ears:

    As you can already see from the technical specifications and introduction, the FiiO F9 Pro is a little different from most In-Ears produced in the past decade and doesn’t only rely on dynamic or Balanced Armature transducers for sound reproduction, but combines both in one shell.

    Most In-Ears use dynamic transducers for audio playback which have the advantage of covering the whole audible spectrum and achieving a strong bass emphasis without much effort. Valuable dynamic drivers are often said to have a more bodied and musical bass that has a more soft impact and decay and lacks of the analytical character that BA transducers are known for. On the downside, in contrast to headphones with other driver principles, dynamic transducers often have a lower resolution.

    Higher-priced and especially professional IEMs mostly use Balanced Armature transducers, which usually have got a higher resolution than dynamic drivers, are faster, more precise and have got the better high-level stability, which is important for stage musicians that often require higher than average listening levels. On the downside, it is usually somewhat difficult (although not impossible) to cover the whole audible spectrum with just one single BA transducer, and a strongly emphasised bass is often only possible with multiple or big drivers. Some people also find In-Ears with BA transducers to sound too analytical, clinical or cold (in several active years in a German audio community where I wrote multiple reviews, gave dozens of purchase advice and help, from time to time I heard people that got into BA earphones for the first time using these attributes for describing BA earphones, especially their lower frequencies).

    Hybrid IEMs unite the positive aspects of both driver principles and use one dynamic transducer for the lows reproduction and at least one BA driver for covering the midrange and highs, wherefore the often as “musical” described bass character remains and the BA transducers add resolution, speed and precision to the mids and highs (, at least in theory) – and that’s what the FiiO F9 Pro does with its technology. It is addressed to those people who perceive the clinically-fast character of BA transducers as unnatural and prefer body and weight, but want to keep the mids’ and highs’ resolution, nimbleness and precision.

    Delivery Content:

    One word: Plenty.


    You don’t only get the in-ears, but also two pairs of cables (single-ended 3.5 mm with in-line three-button remote control and microphone, 2.5 mm TRRS), two storage cases, and last but not least four different sets of differently sized ear tips (3x silicone, 1x foam).

    Looks, Feels, Build Quality:

    The FiiO F9 Pro features a similar shell design as the normal F9, however its colour is different and it has got “Pro” markings on the inner half.
    Build quality is good and the metal shells appear valuable and sturdy.

    The two carrying cases are nice as well and have got soft padding on the inside to protect the ear pieces from scratches. The smaller of the two is, in my opinion, nice if you want to carry around some ear tips or a spare cable, and you can store the accessories in it and then put it inside the bigger hard-case together with the in-ear. Or, if you prefer to carry a smaller bag with you, the smaller of the two cases also offers already enough room for the F9 Pro.

    If you are familiar with DUNU’s more recent in-ears, you will probably immediately recognise the F9 Pro’s standard remote/mic cable, as despite lacking braiding/twisting compared to the other included cable with 2.5 mm TRRS plug, it is very soft and super flexible, and therefore among the best, if not the best, non-twisted cables on the market.
    Apart from directly above the y-splitter that reads “Pro”, there is good strain relief, but unfortunately no chin-slider.
    The ear guides are pre-shaped, flexible silicone tubes without any memory wire. They automatically adjust to the ears’ radius.


    The MMCX plugs sit firmly and tight in the sockets, and what I find nice are the matching coloured side-markers on the cable and the in-ears themselves.

    Oh, and before I forget to mention it: the remote control is really nice since the volume buttons are easy to distinguish and since it doesn’t require much force to push them, yet definition is good and not too soft.

    Comfort, Isolation:

    Thanks to the general shell design that was made popular by Shure and Westone, the F9 Pro sits ergonomically in one’s ears and most people should be able to wear it for hours without experiencing any discomfort.

    Thanks to the nice cable, microphonics are close to being inexistent.


    Noise isolation is on the lower to average side, which was to be expected given the F9 Pro is vented.


    For listening, I mainly used the iBasso DX200 (AMP1 and AMP2 module) and Cowon Plenue 2. The FiiO was always used with the included single-ended cable during comparisons and listening.

    Mainly the largest included white silicone tips were used for listening and all comparisons.

    Frequency response measurements can be found here: http://frequency-response.blogspot.com


    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.
    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 or fully blocked.
    Interestingly enough, in my ears, this vent remains quite free, which is rather rarely the case for my ear anatomy, so all of the following impressions are written with the front cavity vent remaining free.
    Depending on individual ear anatomy, bass levels can also be anywhere in-between.

    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 the Etymotic 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 on the brighter, somewhat 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.
    Balance is good, and while there definitely is some undeniable colouration towards the brighter, leaner side, they still appear mostly well-done although not fully natural, which is in the nature of this tuning that is by the way rather popular among hybrid in-ears coming from Asian manufacturers, and helps focusing on air and clarity. Nonetheless the amount of leanness in the mids, while not as bad as the Fidue A85 (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 quite well-made), might become a bit annoying over time and doesn’t always fit to the singer’s voice – I would say that it works most of the time, but sometimes the vocal timbre can already appear a bit too off.

    Above that, there is a 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 nicely avoided, the 5 kHz elevation adds some metallic-ness to the presentation while the 8 kHz lift tends to a bit of sharpness at times. This is still okay and tolerable 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 a bit nicer for an overall more even and realistic treble presentation. It overall just feels a little “rougher” and “edgier” than comparably bright dynamic driver in-ears, giving the F9 Pro a rather “hard” and unforgiving sound in the highs.



    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.


    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 “empty” space between instruments is pretty clean.


    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.
    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.

    - - -

    Subjectively, I personally prefer the Fidue’s tonal tuning that is a bit 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 slightly leaner 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.

    - - -

    Overall the E1001 is the easier to listen to and more mass-friendly in-ear with its u-shaped tonality, however when it comes to technical abilities and driver coherency, it ultimately loses audibly against the FiiO.


    The FiiO F9 Pro offers really good value, plenty of really nice accessories, has got nice features (replaceable cables plus inline remote control) and build quality coupled with a good, quite precise technical presentation for the price and a hybrid in-ear at this price point, but ultimately lacks some realism and naturalness in the upper mids and treble that can become a bit over-energetic over time and if you don’t like a generally bright signature. Nonetheless it sounds clear, well-separated as well as detailed.

      Brooko likes this.
  3. BulldogXTRM
    Hi Resolution, balanced and low priced
    Written by BulldogXTRM
    Published Jan 19, 2018
    Pros - Balance EQ
    Clear details
    Great soundstage
    Very good resolution
    Cons - No non-mic version
    About Me
    To get started, let me tell you a little about myself.
    I’m a gigging musician (lead guitar/backup vocals), an audio forensic analyst, a novice sound engineer, and an avid music lover with a wide taste in music. Being an audio forensic analyst is a plus I find when reviewing audio products simple because I know what bad audio sounds like and usually know how to correct it. My experience allows me to be familiar with the limitations of my own ears and the equipment I’m using.
    For the consumers, my perspective for all my IEM reviews will be based on these things. I won’t sugar coat things or make things sound better than they are. I’m just like you and I want good value for the money I pay for any product.

    To the manufacturers, I’ll always give you an option to respond to any concerns such as quality that I have during my review. I’ll contact you directly and will do so before my review is published. I want to provide an honest and tangible review for your prospective customers without being unfair to you as a manufacturer.
    I’ll always be fair and my review will be based on my perspective and my experience.
    Now on to the important stuff.

    About the product/expectations
    I received these on loan during a Fiio Review Tour. I really had no expectations going into this except that I believed the F9 Pro would be a competitor in the $150 price range.

    The F9 Pro is built like a tank, metal housing is plus. The cables seem to be good quality, but there was no non-mic 3.5mm cable available.

    After using them for a few days the comfort is very good. The shape of them seems very similar to the Shure SE IEM's and they seat in my ears very similar. Because the housing is metal, they are a bit heavy and when used as a stage monitor, you may have to reseat them after a few songs. Overall they're a good fit.

    The sound on these is outstanding. For the price point that these come in at, most manufacturers are going to have a hard time beating the F9 Pro.

    The lows are clear and tight with a very natural decay. I didn't find any inbalances here and the low end extension resolves well below 20hz. The bottom end never gets in the way of the mids and has enough punch that even bass heads will like these. However the low end seems very balanced and not overly emphasized.

    The mids are are very good with a natural feel. Vocals shine through very well and the mids contribute to a beautifully balanced sound stage. Great separation and ability to resolve different instruments. The mids may sit just a hair behind the high's depending on the source but are still very present and balanced.

    The highs are clear and detailed. No harshness or sibilance that I could detect, very natural sounding with a bit of extension that contributes to the overall clarity of the sound and helps to widen the sound stage. very balanced sounding.

    Compared to UE900s, I found the F9 Pro to have a very similar soundstage, but with more clarity and less low end emphasis. The low end of the F9 Pro seemed to be almost as abundant as the UE900s but with more resolution. The mids and high end was very similar but the F9 Pro had a bit more high end extension which helped to put the F9 Pro just a slight edge on the UE900's for clarity.

    I compared these to the Primo8 and found that the F9 Pro had a more balanced sound, but like the Primo8 depended on the source. The Primo8 sounds very good when using my Samsung Note 8 straight, but the F9 Pro needed a bit more power than my phone could provide I believe. I coupled the Fiio A3 with my phone and the F9 Pro blossomed into one of the best sounding IEM's that I've had the pleasure of using and easily outperformed the Primo8 in everything except mids which is where the Primo8 really shines.

    Based on my findings, I felt these were possibly a top choice IEM for anyone looking for a balanced sound.

    Isolation was good but could have been a little better. I used the provided tips and all of them seemed to seal very good for me. I then used a cheaper "Kinden" foam tip for the majority of my testing due to being able to get a great seal for me.

    I hesitate when trying to gauge value in any product unless there are issues with build quality or the product is just an outstanding value. Based on the $139 price tag as of the time of this review, I would rank the F9 Pro at the top in this price range. I haven't heard anything that will beat them as of yet.

    The Fiio F9 Pro is an outstanding IEM and you would be hard pressed to find another IEM that does as well in this price range. The overall balanced sound, the soundstage and resolution of the F9 Pro is outstanding and I truly believe that is an understatement. The fact that they give you a very well made hard case a decent soft case along with 2 cables (1 3.5mm mic cable, 1 2.5mm balanced cable) and a host of 4 different types of ear tips make these an exceptional value but all of that is overshadowed by the sound quality. Fiio hit a home run with the F9 Pro.
      chupacabra314 and PlantsmanTX like this.
  4. Ynot1
    Fiio Flagship F9 Pro. Yes indeed.
    Written by Ynot1
    Published Jan 6, 2018
    Pros - Fiio flagship with both power handling, spacious presentation, and heighten clarity.
    Cons - I could not find a weakness.
    image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg

    F9pro review

    Welcome to this review. I participated in the headfi tour for the Fiio's flagship hybrid ear phone the F9 Pro; one dynamic driver and two knowles balance armature drivers. And I am writing this review after having spent some time listening to the F9 Pro in my unique way. As the F9 Pro is the newest and the most advanced ear phone to date that I have encountered, I approach this review with a challenge to myself that I would find something to point out in both camps, positive and negative. And what I discovered was that filling the positive camp with observations was easy. But filling the negative camp was not so much as easy. In fact I will explain what happened shortly. The overall rating of this precision engineered F9 Pro is a resounding thumbs up and a recommendation that goes as far as to say life is too short "have cake and eat it too," I'm just saying.

    Ok, where do I begin? Instead of the organized and methodical approach to analyzing like in a school textbook, lets just go all over the place. I say this because the F9 Pro is great at projecting the sound presentation all over the place. It creates a listening environment that is so much like listening to big headphones and even speakers, I am amazed. This to me is very appreciative on a number of levels. For one, I found a headphone that does not mess up my hair in the F9 Pro. And second, bigger is better when it comes to sound, but F9 Pro does this with even more desirable qualities that headphones and speakers simply can not match; i.e. noise isolation, clarity, portability, and so on. Speaking of positives, I could prolly go on and on about the balance armature that there are two knowles and they bring very excellent clarity, separation, and coherence with the rest of the sound presentation. Music with a lot going on is presented like F9 Pro is not breaking a sweat delivering the nuances of the subtle details in each and every sound in the music. In another words, no mud can be found here. I really was impressed how the details in the voices and the strings became evident; where all of the details that a microphone can pick up, the F9 Pro delivers untarnished. And another important factor to mention is how well F9 Pro gets along in the community. For explanation please feel free to continue to the next section.

    The F9 Pro can be enjoyable to listen with or without a dedicated amp/dac. At 28 ohms the F9 Pro can be driven easily by an iPad mini and deliver quality sound. But like all enthusiasts, you should not settle for just good enough. In this field of interest, you should seek out what sounds the best with what you can gain access to, reasonably. And I found out that the F9 Pro had skills. It had skills to be transparent; at least enough to preserve the sound signature of an amp/dac. Ideally both the amp/dac and headphones should be transparent to deliver the source music as intended just like it was at the recording. Anyway my Accessport can be bright and my Walnut V2.1 is warm. And when the F9 Pro was connected to the Accessport, the sounds came through with brightness. And when the F9 Pro was connected to the Walnut, the sound came through with warmth and tenderness; so I did what anyone member of headfi would, turn up the volume. Let me tell you the F9 Pro is a blast to play loud. Because it is so poised at maintaining its resolve; it's impressive. Now there is an inside baseball going on with the Walnut as far as balance armature is concerned. Basically Walnut's high output impedance, like 100 ohms, suppose to sound bad with balance armatures. Apparently the F9 Pro breaks free from this convention and goes where no other balance armatured equipped earphones have gone. Bcause F9 Pro sounds amazing with the Walnut V2.1.

    Back in the day I used to buy a lot of music compilations; this was a period after the mixed tapes era. In those days a lot of mixes were thrown in with the more commonly heard format, the "Radio Edit" version. I suppose those mixes included unique sound manipulations, but who had time to go through them all. So now here I am using my ipad, but some hackers is adding distortion to my right channel. So I took to summoning my savvy intuition and adapted. I pulled out my music and let it lose on the F9 Pro connected to the Walnut as amp and the Benjie X1 as source/dac in shuffle mode. Since I haven't heard a lot of the mixes, this experience was more than entertaining; it was discovery and I was excited. But more importantly I was blown away at how good the F9 Pro was in delivering the music. Everything sounded fresh and new like I have never heard before; hearing things in the music in a way that I have never heard before. In essence the F9 Pro made it seem like I bought a whole lot of new music. And from an economist point of view I'm saving a lot of money getting the F9 Pro. I know right, economist knows how to get us into financial trouble; cause often they're only right half of the time, but I digress.

    Some break down info in a quickie format:

    Bass: F9 Pro has mid bass, regular bass, and sub bass no questions asked. But it does not have basshead bass that is always there on everything you play, unless you play only basshead music. In fact the bass has quality in the form of distinction in the bass band, never muddy. I like.

    Mids: F9 Pro is clear with great separation in the mids. Voices and instruments can be very revealing with the right setup. I like.

    Treble: F9 Pro has the means to deliver the treble honestly, but I prefer to tone down the brightness for the sake of longevity. And depending on the amp/dac used F9 Pro can be versatile and deliver the sound signature that I want. And F9 Pro is good in this way. I like.

    Negative camp:
    I tried my hardest to find a weakness in the F9 Pro by using the gear that I have, but to no avail. I concluded either there is no weakness to be found or I simply need better gear to evaluate F9 Pro better.

    On a different note, this is negative camp for me because I reviewed the Fiio Q1 MK II which I thought was great in the balance mode. However I did not have access to this amp during this review. And therefore I can only imagine how much greater the F9 Pro could have brought to my listening experience in the balance mode. Especially knowing that the F9 Pro is great at handling power and space at the same time.

    On a related note, I could not verify the mic and volume up and down button due to hacking on my ipad mini.

    Fiio has improved upon the F9 with the F9 Pro and I trust it is so. Because my evaluation of the F9 Pro is that it is truely worthy of its flagship status. F9 Pro does everything well. And I learned my inventory of gear can not find a fault with the F9 Pro. It is that good. So I apologize to the reader as I have failed to reveal a weakness in the F9 Pro.
    1. FiiO
      Thank you so much for the nice review. Yes, the F9 PRO is not MFi certified, so the volume is not valid using on iOS system. With the removal of 3.5mm port on new iPhone, to get the MFi certification that may only available to iPhone 6s and former version, but will result in longer delivery time and higher cost, so we have no choice but to made the compromise.
      FiiO, Jan 7, 2018
      Ynot1 likes this.
  5. Wiljen
    Fiio F9 Pro - This is how you earn the name PRO!
    Written by Wiljen
    Published Jan 4, 2018
    Pros - They fixed the glitch! No more spike at 7 kHz. Excellent build, good extension at both ends, nice listenable signature.
    Cons - Treble still a bit hot. Tuning tips muddy the sound and are not particularly useful.
    A big thank you to Fiio for including me in this review tour. As I write this, the F9 Pro is waiting for the PO to head to the next lucky tour member.


    Fiio and I have grown up together. Some of my first audio gear had the Fiio name on the side of it. An E17 with an E09 graced my office desk for quite some time a few years ago. As Fiio has matured, so have their products. Their DAPs are now the standard by which any sub $500 DAP is measured if you look at all the comparisons they draw in reviews. Not too long ago, I was asked to review a first for Fiio, an earbud. They had added the rest of the equation to their product line as they had long had amplifiers, digital to analog converters, and digital audio players, it was time to add earphones. That initial earbud was a great listen and was a hint at things to come. First, they paired with Dunu to release the EX1, their version of the Titan. I skipped that one, as I already owned a Titan and did not see a need for another. Then came a brand new line the F series. The F1,3,and 5 are all dynamic driver based and as you go up in sequence the resolving power of the drivers also move up. I purchased the F5, which was an improved EX with a titanium diaphragm and improved extension on both ends. They did a good job of showing what Fiio had learned from the earlier generations. Next was their BA/Dynamic hybrid the F9. After having liked the F5, I wasted little time in placing an order for the F9 only to be a bit disappointed. While the F9 had good clarity, more than expected levels of detail and good extension, it also had a major problem. A treble spike in the middle of the lower treble range absolutely ruined an otherwise good experience. Therefore, the F9 sits in the drawer while I moved on to the Brainwavz b400. Then Fiio announced the F9 SE – which was a fixed cable budget version of the F9 with no other changes. Then I was reading one day and a Fiio representative had posted on the upcoming release of the F9Pro, which got my attention, as the change was the in-house BA was replaced with the Knowles TWFK-30017 BA. My immediate thought was “Will this fix the spike?” Luckily, for me, Fiio sent me a sample of the F9Pro as part of their review tour. Did they succeed – read on?


    The F9 Pro comes with a very complete kit. Starting with a premium feel to the packaging. The box has an outer cardboard box with typical western style product details and advertising.


    Inside the outer box is a black pressboard case with an understated Fiio Logo. Opening the box reveals well-fitted compartments for the earpieces at the top and a pelican style hard case below it.

    Tips are hiding under the earpieces and quite a selection is provided (three different sizes of four different styles of tips) (More on this below). Inside the Hard case is a soft case made of something close to sweatshirt material, and two cables. The hard case is well padded and is similar to the Dunu provided pelican cases, which may hint that a partnership between Dunu and Fiio is still lurking in the background.


    While well designed to provide protection from water and abuse, the hard case is too large for pocket carry so the soft case is a much-appreciated addition to the accessory package.


    A 3.5mm terminated single ended cable with a microphone and remote and a 2.5mm terminated balanced cable devoid of the mic/remote are provided and hiding under the tips. (Personal bias is for cables without remotes so I used that most of the time unless testing the mic/remote.)

    Tips deserve their own conversation here as the tips provided are designed to do different things. Fiio provides a set of memory foam tips that have the typical effect of dampening treble a bit and providing great isolation. In addition to the foams, three styles of silicone tips are provided. One style provides a neutral signature while the other two enhance either bass or treble. All my testing has been done with either neutral or foams (I did not use the provided foams since this was a review tour).


    The F9 series all share the same 2 piece metal shell. It is well made with seams being very consistent and no major gaps or glue showing. All of the F9 variants with removable cables use an mmcx connector for cable attachment on the upper side of the housing. This does limit the design to over-ear cable wear with the provided cables due to the built in guides. After-market mmcx cables without a memory wire can allow cable down wear but the fit is sub-optimal, as the weight of the cable tends to pull on the upper side of the shell and cause problems with seal and isolation. There are two vents on the inside of the shell (one immediately behind the nozzle and one immediately beneath the mmcx base). These do somewhat limit isolation but wear in a noisy office or public transport is still very viable.

    The mmcx connector is at a slightly greater angle than the F9 so cables with larger connectors (Veclan) now fit well. (On the original F9, you had to shave some connectors to get a proper fit). Red and blue markings exist on the body of the mmcx connectors with matching coloration on the tip of the cables for easy reference.

    Cables themselves are well made with solid rubber housing around the mmcx with a colored ring to show left/right orientation. Plastic memory guides provide the strain relief, which is a much better arrangement than memory wires in my opinion. Gentle heat with a hair-dryer will allow for reshaping should it be desired. Cables themselves are supple and minimize microphonics well. There is no chin slider, which I’m sure will be a detractor to some, but I found it unnecessary as fit, was good without it and no issues with movement presented during use. The splitter is metal and colored to match the earpieces with the word pro in white lettering.

    A strain relief is added at the lower side of the splitter. The cables terminate in a 90 Degree 2.5 or a 3.5mm jack.


    The 2.5mm cable is braided all the way throughout while the 3.5 is cloth wrapped. Both cables have cable management ties made of soft rubber just above the jack. This is a welcome addition and I found the soft rubber was easy to ignore if not in use. For those that dislike them a quick and careful cut with a razor knife should have them gone in a matter of a moment.

    The Mic/remote on the 3.5mm cable matches the color of the earpieces as well and is straightforward and simple to use. It is worth noting that the microphone is susceptible to movement noise due to its position on the backside of the remote where it will be directed toward your clothing during normal wear. A shirt clip would be advisable if you intend to use the phone while at the gym or other strenuous exercise to minimize this.

    The color of the F9 pro is much closer to that of The X5iii and the A5 I recently reviewed so if that is something that concerns you, you can rejoice. The original F9 was a distinct mismatch in this department but was never a concern for me.

    I found the fit of the F9 pro to be very similar to the original F9 with a slightly greater forward rake to the nozzle than the original. Isolation was good but very tip dependent, as they are not a super deep fit.


    Let us go ahead and get it out of the way. Did they fix the spike? The answer is maybe. The spike has moved up the scale from the 7 kHz region of the original F9. My guess would put it at high 8 kHz / low 9 kHz range based on what EQ settings remove it. The great news is, it is much less obtrusive than the previous version to my ear and probably many others. The bad news is technically, there is still a spike and it still contributes to the overall sound signature. Having said that, I am very pleased with the improvements the Knowles drivers made to the F9 Pro and I think it is big improvement in the treble overall.

    For me, I like a headphone/earphone to have a good sub-bass presence, moderate mid-bass with as little bleed into the mids as possible, slightly forward upper mids with good vocals, and enough air and sparkle to get my attention. I tend to lean toward bright signatures as long as sub-bass is present.

    The F9 Pro nearly matches my preferred signature. It is nearly linear with a mild U shape with plenty of sparkle without being belligerent. Bass is enhanced beyond neutral, but not emphasized to the degree commonly seen in V shaped signatures. Mids are clear with lower mids being very slightly recessed but upper mids pushed slightly forward almost exactly in the presence region so vocals are well rendered and natural sounding.


    I expected the F9 Pro to share the same bass as the F9. Let me say immediately, it does not. This may be a case of addition by subtraction as the change in the treble elements may have revealed more of the bass, but the Pro has a more pronounced sub-bass and lower bass without being bloated in the mid-bass region. The F9 Pro’s bass seems to have greater extension and retains the good punch and slam of its progenitor. The mid-bass is very slightly forward but bleed into the mids is minimal. My advice would be to avoid the bass enhancing tips as they only serve to bloat an otherwise very good bass.


    The lower mids are slightly recessed or maybe it is because the upper-mids are slightly forward the lower range seems recessed. Female vocals benefit greatly from the slight push to the upper mids while Male vocals sound full and natural. I was particularly impressed with the rendering of Van Morrison’s vocals (One of my heroes). Guitars have a nice full-bodied tone without being bloated and while retaining great definition and detail. Although, not a warm signature, the mids do have some elements that produce a smooth, organic tone more typically found in warmer signatures.


    I was not a fan of the original F9’s treble. Unfortunately for me, the spike at 7 kHz was in a range that absolutely fatigued my ears and ruined the experience in short order. I understand that others were not bothered by this and my wife was amongst them. She uses my F9 infinitely more than I do these days as a result. I borrowed them back long enough to compare and make sure my memory was correct. What I found was the Pro has a more domesticated treble with better table manners. The lower treble is more linear when compared to the F9 with a mild boost in the mid treble that leads to a bit of extra energy for cymbals. The tuning is enough better on the Pro that more detail is presented (probably addition by subtraction again) when compared with the F9 and extension is slightly better with a bit more air and sparkle.

    Imaging and Soundstage

    I found imaging on the F9 Pro to be quite good as directional cues are well presented and the pro does a good job of layering without losing those directional cues in busier passages. Soundstage is wider than it is deep and is above average for its class.


    The F9 Pro works well from my HTC M9 or I-phone 7 without an external amplifier, but I did find it scaled well and was particularly enjoyable using the Cayin N3 and a resistor modded Walnut F1 (18K Ohm in parallel with Muses op-amp to lower gain). I think the F9 Pro also is easier to pair than the original F9 due to a slightly warmer tone.


    Fiio F9: The obvious aside (ergonomics etc. being equal), the biggest difference in the PRO is the sound signature. The Treble spike that intruded into listening is gone on the Pro and the whole signature opens up as a result. Sub-bass is more present, mids are a bit more forward, and vocals are natural and well rendered. The strident and sometimes sibilant nature of the F9 is resolved in the F9 Pro and makes the listening experience much more enjoyable.

    B400: The brainwavz has been a daily driver for me, so the question is, can the F9 Pro unseat it? From a fit and finish prospective, the F9 Pro gets the nod, as its metal shell and finish are about as comfortable as the b400, but the peeling paint on the seams of the 400 are a reminder that the construction methods differ quite a bit. From a sound perspective, the two are very hard to compare as the b400 is near reference flat and the F9 Pro is much more U shaped. The b400 shows a bit warmer signature compared to the F9 Pro’s bright leanings. Both have good extension although the F9 may have just a hair better extension at the low end. That said the b400 definitely wins on speed. Attack and decay are tighter and details benefit accordingly. With these two, it is going to come down to preference and you cannot go wrong with either. I love my b400s, but will make a place in my routine for the F9 Pro as well.

    AKG n40: The n40 is more compact than the F9 Pro but fit and isolation are about the same. Both are designed for over-ear cable wear and both use very similar designs to the shells with ports to the inside of the shell. The F9 Pro has more low-end slam, while the n40 has slightly better extension at the top end. Signatures are very different with the F9 being much more aggressive and the n40 being much more laid back. The n40 lacks some of the detail in the upper mids of the F9 and has slightly less sparkle in the top end but more air at the very top. The n40 provides a very non-fatiguing listening experience while the F9 Pro brings additional details to the surface at the expense of a slightly harsher listen. I think owners of the b400 or F9 pro may find the n40 a bit of a disappointment as it has little in the way of technical enhancements over the others at nearly double the price.

    Magaosi K5: The K5 is nearly as resolving as the F9 Pro but suffers from a low-level hiss when paired with high-powered sources. When run from a source it pairs well with, the K5 is a bit warmer than the F9 Pro. Where the K5 really loses, ground is in bass extension. The F9 Pro has considerably deeper bass and much more sub-bass presence. Considering the F9 Pro has a suggested retail $30 below that of the K5 there is really no reason to consider the K5. The F9 Pro is a marked improvement over the K5 in nearly every category.

    1More Quad: Build quality is a wash or a very slight advantage for the one more Quad. The F9 Pro has a big advantage when it comes to fit and isolation though due to the odd shape and weight distribution of the Quad. Removable cables are another plus for the F9 Pro. Signatures are very different with the Quad being warm and dark while the F9 Pro is brighter if a bit thinner. The Quad tends to have a bit bloated upper bass which can at times bleed into the lower mids. This gives the F9 Pro a distinct advantage in definition and clarity while the mids of the Quad can seem a bit cloudy or murky at times. The Upper end of the signature is also very different. The Quad is more laid-back while the F9 Pro is a bit more forward and aggressive on the upper end. Extension on the upper end is better on the F9 Pro which gives it an overall cleaner more transparent signature that presents more detail than the Quad. Technically, the F9 Pro is the better choice, its hard to knock the Quad though as while it lacks some of the transparency of the F9 Pro it has a very listenable signature. If you wear them on the go, the F9 is a clear winner as the weight distribution of the quad makes them tough to wear while moving and maintain a good fit.

    Trinity Icarus III: I used an Icarus III with the green nozzles as my daily driver for a good while and with price points being similar (pre-order) I thought I would include them here. Cables – F9 Pro wins hands down. I much prefer the cable style of the F9 to that of the Icarus. Sound wise, the Icarus is much warmer compared to the bright signature of the F9 Pro. Even when using lean filters, the Icarus tends to have some bass bleed into the upper mids and suffers from lack of details in the mids because of being obscured by the bass bump. The plus for the Icarus is more bass slam and better bass extension. The Icarus can be a bass monster depending on filters while the F9 pro renders more detail and is much more neutral.



    I had high hopes for the F9 Pro as the F9 checked a lot of the right boxes for me, but having recently purchased the b400, AKG n40, and the F9, I was reluctant to spend more to purchase the F9 Pro on the chance that it was enough improved when compared to the original F9 to warrant the purchase. Having now had the opportunity to use the F9 Pro for a week as part of this tour, I can say I should not have been reluctant to purchase the F9 Pro in the least. The F9 Pro easily ranks among the best in-ears I have tried in the sub $300 price range. The things the F9 did well are still there and some are improved. The things the F9 did poorly have been addressed and are no longer issues. Bravo to Fiio for listening to customer feedback and making the changes. Fiio has done what some would have said was impossible, gone from startup earphone maker to class-leading performance in less than 24 months. I cannot wait to see what is next from Fiio. Maybe an over-ear?


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  6. ryanjsoo
    Fiio F9 Pro Review - Pure Clarity
    Written by ryanjsoo
    Published Dec 13, 2017
    Pros - Great build and ergonomic, Excellent treble extension, Detailed, Relatively balanced, Tuning tips
    Cons - May still be too bright for some, Average isolation, Still not especially linear
    Introduction –

    Fiio have grown from a small manufacturer to an industry juggernaut in the span of just a few years due to their competitive pricing, eye-catching designs and consistent performance. Their myriad source devices played an integral role in their popularisation but with competition filling the market to saturation, it is clear that other innovations represent the next evolution of Fiio. The F9 was that essential Fiio in-ear for the vast majority, an earphone that thrived on clarity and detail presence.

    However, that earphone also had critic dividing flaws, most notably, a treble spike within the lower treble that could make it sound quite unnatural. As such, Fiio have produced the F9 Pro, a continuation of original utilising the same triple hybrid driver setup but with improved balanced armature high-frequency drivers. This is an interesting progression of the F9 and certainly a step in the right direction while retaining a lot of the charm of the original. Let’s see whether the Pro’s refinements justify its increased $145 asking price.

    Disclaimer –

    I would like to thank Sunny from Fiio very much for her quick communication and for providing me with the F9 Pro for the purpose of review. All words are my own and there is no monetary incentive for a positive review. Despite receiving the earphones free of cost, I will attempt to be as objective as possible in my evaluation.

    Accessories –


    The F9 Pro has a comprehensive unboxing congruent with Fiio’s other offerings. The earphones come with a bolstered accessory set when compared to the original model, comprising of the same terrific pelican style hard case in addition to a plethora of ear tips. Fiio also provide a small zippered fabric case that is far more portable, not to mention pocketable.


    Regarding tip choice, Fiio include various types of tips, each with their own distinct sound; 3 pairs of bass eQ tips, 3 pairs of standard tips and 3 pairs of firmer, brighter tips. Fiio also include 3 pairs of one-size fits all memory foam tips that dampen the treble slightly and provide greater noise isolation. Underneath are the two cables, a braided balanced unit and a regular 3.5mm cable with a remote/mic.

    Design –

    The original F9 was an impressively constructed earphone and the Pro is mostly identical but with subtle tweaks that elevate the user experience. The most noticeable change stems from the Pro’s new colour scheme, assuming a lighter, bluer hue of grey that better coordinates with Fiio’s sources. The MMCX angle has also been adjusted, now accommodating cables with bulkier MMCX connectors such as the Penon OS849. In addition, the Pro has coloured indicators on the inner face of each earpiece that enables easy orientation.


    Otherwise, the experience is very much the same, the F9 Pro carries a solid aluminium build with a satin texture. Ripples propagate along its face producing a very dynamic aesthetic in addition to some additional tactility when swapping cables. The earphones are smoothly formed and ergonomic with a medium fit depth. They have a perfectly angled stem with a lipped nozzle fitting the majority of ear tips such as Sony Hybrids and Spinfits.


    Due to a multitude of vents on the inner face of each earpiece, the F9 Pro provides just average levels of isolation, just sufficient for public transport but they’ll get drowned out in louder environments. They are relatively low-profile and can be slept in comfortably, they also produce average amounts of wind noise despite their rippled texture. The F9 Pro wears comfortably, with a minor ache forming at the rear of my ears after several hours due to their slightly larger dimensions.


    The F9 Pro utilises a removable MMCX cable system. The connectors are very tight and clicky, and though my left earpiece was notably looser than my right one, this didn’t produce any intermittency. It would seem that Fiio have appended the issues that afflicted the F5. The standard remote cable is mediocre, rubbery and thin with adequately relieved terminations. The mic is quite clear and the buttons worked perfectly on both my HTC U11 and iPod Touch 6G. The balanced cable is a lot nicer, however, with a 4-wire braid and smooth, incredibly supple sheathing. The cable has nice metal connectors with an improved right-angle plug that is far better relieved than that on the F9. The earguides are pre-formed rather than using memory wire, they were well shaped and stable for my ears.

    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.

    Comparisons –


    Fiio F9 ($100): Both are similar in design with identical ergonomics. Of note, the Pro assumes the design of later revision F9’s. Unsurprisingly, the Pro also sounds similar to its progenitor and the most immediate differences stem from the treble response which isn’t as peaked on the Pro. As a result, the Pro is more balanced, notably smoother and more bodied. Bass slam is relatively increased and lows are both fuller and more defined overall due to lesser mid-bass focus. Mids are similarly present and both carry a more clarity orientated sound. However, the Pro has greater body and sounds considerably more natural and less sibilant due to its more linear nature.

    Lower mids have notably increased body, making instruments sound a lot more realistic in timbre. Within the higher-frequencies, the Pro is immediately more detailed and more separated while remaining revealing, clear and airy. Extension is improved and the highest notes are far better resolved. The Pro produces a similarly sized stage but imaging is improved and separation is just as strong. The differences aren’t enormous (and, for that matter, neither is the price jump) but they do culminate to produce a notably enhanced listen.

    Simgot EN700 Pro ($150): The Simgot is a much larger earphone but one that finds a similarly comfortable fit. Neither isolate well, both sport a removable cable but the Simgot 8-core unit looks and feels more substantial while remaining practical. The EN700 Pro is the smoother, warmer and more laid-back earphone while the F9 Pro is more u-shaped and engaging. The F9 Pro delivers firmer sub-bass slam while the EN700 Pro focusses on greater mid and upper-bass body and is warmer in tone as a result. The F9 Pro has a tighter bass response with a more neutral tone possessing greater transience and higher definition. The F9 Pro has a slightly drier, more recessed lower midrange while the EN700 Pro sounds a little clearer and a little more present but also warmer and more bodied.

    The F9 Pro delivers a clearer, more present upper midrange. Female vocals sound more immediate but both are very clear yet naturally voiced. The F9 Pro delivers notes with greater attack while the EN700 Pro leans towards the smoother side with a more refined treble response. The F9 Pro is unsurprisingly crisper and brings micro-details more to the fore while the EN700 Pro is well-detailed but less concise in its delivery. The F9 Pro has better treble extension and far greater air up top but it may fatigue those unacclimatized to a brighter signature. Despite this, the EN700 Pro is notably more spacious, perhaps on account of its design. Both image very well, the F9 Pro has better separation. The Fiio will suit analytical listeners, the Simgot is more musical and listenable long-term.

    Meeaudio Pinnacle P1 ($200): The P1 is smaller and produces a more stable, isolating fit. It has a solid removable cable and can be worn both cable up and down. The Meeaudio pursues a similar brighter tuning but it is less linear than the F9 Pro and slightly more engaging. Sub-bass extension is better on the F9 Pro and sub-bass impact is greater. The P1 produces a notably warmer mid-bass response yet it is tight, agile and well-controlled, delivering more defined notes than the Fiio with greater punch. Lower mids are more scooped on the P1 but both are similarly clear and defined. The P1 sounds slightly more organic due to its increased warmth. Upper mids have similar presence but the F9 Pro has greater clarity at the cost of realism where the P1 is more refined and nuanced in its delivery. The P1 has a similarly boosted lower treble response, it isn’t quite as bright as the F9 Pro, but also isn’t as linear into the higher frequencies.

    As a result, they both retrieve similar details with similar aggression, the P1 has perhaps even greater attack but this does comprise texture and realism. The P1 smooths off above again, like the F9 Pro, and both extend very well. That said, the F9 Pro is more linear and resolving within the upper registers. The P1 has a wider stage than the F9 Pro while the Fiio has more depth. The P1’s greater speed and midrange resolution grant it with similarly accurate imaging, but the more vivid Fiio does separate a little better. Both are incredibly resolving earphones considering their asking price, the P1 has superior ergonomics and sounds a little more natural within its midrange while the F9 Pro is more resolving up top.

    1More Quad Driver ($200): The 1More is more meticulous in its construction but the F9 Pro holds a large ergonomic and isolation advantage. It also has a removable cable that the Quad Drive lacks. The 1More Quad Driver is warmer, more bodied and darker throughout. It has more bass emphasis with a tighter sub-bass impact mated to larger mid-bass slam, imbuing its presentation with warmth and body. The Quad-Driver also has greater upper bass elevation, it sounds tubbier, slower and less defined but also denser and more impactful. Lower mids are warm yet well-defined on the 1More, they are a little more present than the F9 Pro but lack the same clarity and transparency. Upper mids are very different, the 1More is darker and thicker, female vocals are far more laid-back but still possess nice layering and resolution.

    The F9 Pro is more forward with far greater clarity and aggression into its lower-treble. The Quad-Driver has a considerably more laid-back lower-treble response that sounds crisp but lacks a lot of attack and foreground detail in comparison to the Fiio. The 1More has a spiked middle treble that can sound a little tizzy where the F9 Pro is more linear. The F9 Pro has better extension despite its lower driver count and treble is considerably more resolving and defined than the 1More overall. Both construct a large stage, the Fiio is a little larger though the 1More sounds very multidimensional, quite a unique trait to this earphone. On the contrary, the clearer, more neutral Fiio separates a lot better. The Fiio is easily the more technical earphone but the 1More’s smoother sound is less fatiguing and it has a more standard fit.

    Verdict –

    Though almost identical on the surface, some small but very intentional tweaks here and there produce a considerably more compelling experience than previous models. With slightly updated cosmetics and a more practical MMCX solution, the new Pro is also more pragmatic than ever before. The biggest upgrades no doubt arise in listening where the Pro’s wider band treble emphasis and more balanced, linear tuning create a notably more discerning listen. And despite their increased price, the Pro ends up being far better equipped than the regular F9 to challenge similarly priced competitors, representing a fine step up from the heavy hitters in the $100 category.


    Because I have no hesitation donning the F9 Pro one of the most technically impressive earphones I’ve heard around this price; achieving clarity through resolution, separation and air through extension and engagement through transience rather than relying on unnatural peaks and troughs. Of course, the F9 Pro isn’t without its issues, they still don’t isolate especially well, their tubbier housings aren’t perfectly comfortable and their revealing signature comes at the cost of outright realism and some fatigue over time, but Fiio’s latest competes head-on with some highly regarded earphones one price class up.

    Verdict – 9/10, The F9 Pro, though still bright and aggressive, isn’t quite so analytical as its predecessor with hints of additional body, warmth and smoothness soothing the aggression of its revealing tonality. It is not only a resolving earphone, but an engaging one, just don’t expect an aboslutely natural or musical presentation.

    Thanks for reading! If you enjoyed my review, please see my website for more just like it:
      WholeMilk, FiiO, Suneerat and 5 others like this.
  7. Brooko
    FiiO F9 Pro - Excellence On A Budget
    Written by Brooko
    Published Dec 6, 2017
    Pros - Sound quality, build quality, overall design, balance, fit, comfort, value, balanced and SE cables, accessories
    Cons - Very slightly over energetic lower treble - but many may like this tuning
    Picture are default 1200 x 800 resolution - click to view larger images.

    FiiO have been expanding their earphone range recently, and I've been fortunate enough to be part of their journey – testing and reviewing their very early releases, and watching them mature in a very short time period. The difference with FiiO is the speed at which they've advanced, and also the quality of their products (given the very short time they've been in the earphone game). I reviewed their F9 in September, and it was a real game changer. Permanent material triple driver hybrid IEM with SE and balanced cables, and coming in at a miserly $100. The fit was superb, and the sound was excellent (barring one little obtrusive lower treble peak).

    Two months later, and FiiO have now released their “Pro” version of the F9. So what has changed, and has it improved on the original? Lets put it through it's paces.


    By now, most Head-Fi members should know about the FiiO Electronics Company. If you don’t, here’s a very short summary.

    FiiO was first founded in 2007. Their first offerings were some extremely low cost portable amplifiers – which were sometimes critiqued by some seasoned Head-Fiers as being low budget “toys”. But FiiO has spent a lot of time with the community here, and continued to listen to their potential buyers, adopt our ideas, and grow their product range. They debuted their first DAP (the X3) in 2013, and despite some early hiccups with developing the UI, have worked with their customer base to continually develop the firmware for a better user experience. The X3 was followed by the X5, X1, X7 and most of these DAPs are now into their 2nd or even 3rd generations.

    They've also developed new cables, desktop and portable amplifiers, DACs, ear-buds and earphones. FiiO’s products have followed a very simple formula since 2007 – affordable, stylish, well built, functional, measuring well, and most importantly sounding good.


    The FiiO F9 Pro IEM that I’m reviewing today was provided to me gratis as a review sample. Although I have made it clear to FiiO on many occasions that I still regard any product they send me as their sole property and available for return any time at their request, they have told me that the product is mine to do with as I see fit. So I thank them for the ability to continue use of the FiiO F9 for follow up comparisons. I do not make any financial gain from this review – it is has been written simply as my way of providing feedback both to the Head-Fi community and also FiiO themselves.

    I have now had the FiiO F9 Pro IEM for 3 weeks. The retail price at time of review is ~ USD 139.

    PREAMBLE - 'ABOUT ME'. (or a base-line for interpreting my thoughts and bias)

    I'm a 50 year old music lover. I don't say audiophile – I just love my music. Over the last couple of years, I have slowly changed from cheaper listening set-ups to my current set-up. I vary my listening from portables (mostly now from the FiiO X5iii, X7ii and iPhone SE) to my desk-top's set-up (PC > USB > iFi iDSD). My main full sized headphones at the time of writing are the Sennheiser HD800S, Sennheiser HD600 & HD630VB, MS Pro and AKG K553. Most of my portable listening is done with IEMs, and it has mainly been (for pleasure) with my own personally owned IEMs - the Jays q-Jays, Alclair Curve2 and LZ Big Dipper. A full list of the gear I have owned (past and present is listed in my Head-Fi profile).

    I have very eclectic music tastes listening to a variety from classical/opera and jazz, to grunge and general rock. I listen to a lot of blues, jazz, folk music, classic rock, indie and alternative rock. I am particularly fond of female vocals. I generally tend toward cans that are relatively neutral/balanced, but I do have a fondness for clarity, and suspect I might have slight ‘treble-head’ preferences. I am not overly treble sensitive, and in the past have really enjoyed headphones like the K701, SR325i, and of course the T1 and DT880. I have a specific sensitivity to the 2-3 kHz frequency area (most humans do) but my sensitivity is particularly strong, and I tend to like a relatively flat mid-range with slight elevation in the upper-mids around this area.

    I have extensively tested myself (ABX) and I find aac256 or higher to be completely transparent. I do use exclusively red-book 16/44.1 if space is not an issue. All of my music is legally purchased (mostly CD – the rest FLAC purchased on-line). I tend to be sceptical about audiophile ‘claims’, don’t generally believe in burn-in, have never heard a difference with different cables (unless it was volume or impedance related), and would rather test myself blind on perceived differences. I am not a ‘golden eared listener’. I suffer from mild tinnitus, and at 50, my hearing is less than perfect (it only extends to around 14 kHz nowadays). My usual listening level is around 65-75 dB.

    For the purposes of this review - I used the FiiO F9 Pro straight from the headphone-out socket of many of my portables, but predominantly the X5iii, X3iii, X7ii and my iPhone. I did not generally further amp them (I did test them with my Q1ii, A5, and XRK NHB pocket amp ), as IMO they do not benefit greatly from additional amplification (YMMV and it may depend on your source). In the time I have spent with the FiiO F9 Pro, I have noticed no change to the overall sonic presentation (break-in). Time spent now with the F9 Pro would be approximately 25-30 hours.

    This is a purely subjective review - my gear, my ears, and my experience. Please take it all with a grain of salt - especially if it does not match your own experience.

    You may notice large parts of this review are similar to my F9 review – its simply because the design and much of the tests I ran are similar – so it was far easier to simply follow the last review. Some may see this as lazy – but it gives me a chance to get impressions out sooner. I followed the same meticulous testing and did not cut corners in gathering the information.


    The FiiO F9 Pro arrived in an approximately 110mm x 165mm x 53mm retail box with a picture of the F9 Pro on the front cover. Its essentially the same sized box as on the F9 – but includes the “Pro” designation and reference to the Knowles dual BA driver. Inside the retail outer is a black box and lid – simply adorned with the FiiO logo.

    Inside you get a black glossy Pelican case, the F9 Pro in a cut-out foam enclosure, but this time a step up in accessories. You get the two cables – one is single ended with on-cable Android controls, and the other is a very flexible balanced cable. You also get 4 sets of tips (3 different silicone and 1 set of foams), the usual manuals, and one soft carry case.

    [​IMG] [​IMG]
    Retail boxFull package contents

    The storage case is very similar to the Dunu Pelican type cases, has internal measurements of ~ 98mm x 58mm and approx 34mm deep. It is rigid with felt like internal padding and provides pretty good protection as well as storage. Because of it's size, its more suited to jacket pocket than pants pocket use.

    The new pocketable soft-case is (IMO) brilliant. Its essentially a neoprene fabric clamshell (zipped) which has sufficient padding to protect, but is small enough to fit in a pants / jeans pocket. Apparently it is also water resistant. I absolutely love it.

    So a step-up on the original F9 package for sure – so far, so good.

    [​IMG] [​IMG]
    Pelican and soft caseTip Selection

    (From FiiO's packaging / website)
    ModelFiiO F9 Pro
    Approx price$139 USD
    TypeTriple Driver Hybrid
    Driver DD1 x 9.2mm Titanium DD
    Drivers BA1 x dual BA Knowles TWFK-30017-000
    Freq Range15Hz – 40kHz
    Sensitivity106 dB /mW
    Cable1.2m, replaceable (MMCX) x 2
    Jack3.5mm gold plated right angled
    Weight21g with default cable
    Casing materialAnodised CNC aluminium alloy


    The graphs I use are generated using the Vibro Veritas coupler and ARTA software. Ken Ball (ALO/Campfire) graciously provided me with measurement data which I have used to recalibrate my Veritas so that it mimics an IEC 711 measurement standard (Ken uses two separate BK ear simulators, we measured the same set of IEMs, and I built my calibration curve from shared data). I do not claim that this data is 100% accurate, but it is very consistent, and is as close as I can get to the IEC 711 standard on my budget.

    I do not claim that the measurements are in any way more accurate than anyone else's, but they have been proven to be consistent and I think they should be enough to give a reasonable idea of response - especially if you've followed any of my other reviews. When measuring I always use crystal foam tips (so medium bore opening) - and the reason I use them is for very consistent seal and placement depth in the coupler. I use the same amp (E11K) for all my measurements - and output is under 1 ohm.

    The graphs are provided merely as a point of discussion, and later in the review I've included comparisons to other IEMs for similar reference.


    My quick sonic impression of the FiiO F9 Pro – written well before I measured:
    • Bass is very linear but also has good extension, with a small mid-bass hump. There is audible sub bass rumble but it is in balance with the rest of the signature and does not overpower.
    • Lower mid-range is also reasonably linear, with a light recession. Both male and female vocals are well represented and sound quite natural. Upper mid-range is emphasised, and reaches a peak in the presence area. Female vocals have a a very good sense of euphony, and there is good cohesion and transition from lower to upper mid-range.
    • Lower treble extension is good and there is a little heat further up the lower treble, but this time it does not create the occasional harshness I got from the original F9.
    • The Pro manages to take everything which was good about the original F9 and recreate it, but this time without the occasional heat from the problematic 7 kHz spike. I later found out that it has been moved a little more into the 8-9 kHz range, and for me becomes less obtrusive.
    • Channel matching is good on the pair I have – very good in the mid-range and treble, but the dynamic drivers are slightly out (its not noticeable with music).


    The FiiO F9 Pro (like the original F9) is beautifully built and seeing what FiiO can do for really does make me question how so many other companies struggle to get ergonomic design right. The main body is CNC'd, sand blasted and then anodized for a really nice metallic finish. The colour this time is a really nice titanium rather than the darker obsidian colour of the original. There is a design on the outer shells, but even that is devoid of hard edges. The entire shell is beautifully rounded and sized to perfection

    The F9 measures approx 21mm across with a total height (including cable exit) of 17mm, and depth of 12mm.The nozzle is angled forward and extends approx 6mm from the main body (so relatively shallow fitting). It is 5mm in diameter with a generous lip and mesh protective cover.

    [​IMG] [​IMG] [​IMG]
    External face viewFront viewInternal view

    On the internal face of each unit are two ventilation ports and a L or R designator. The cable exit uses an MMCX connector and this is situated on top of the main body, and naturally forward. The connectors are tight, and although they do not sit flush with the main body, they still feel very sturdy. The other changes from the original F9 is the small red or blue marking on shell next to the MMCX socket (makes IDing left or right very easy), and also the angle of the cable exit (allowing other after-market cables to be used more easily).

    The F9 Pro comes with two included cables – a standard 3.5mm stereo which has in-line mic, volume and playback controls, and also 2.5mm balanced cable option. Both cables have a hard rubber / moulded plastic housing for the MMCX connector which then joins to preformed flexible ear-hooks which are extremely comfortable and keep the IEM in place brilliantly (I love this design). On the MMCX mating collar are either red or blue markings which makes determining left or right very easy, and FiiO have also added knurling to the cable ends to make grip easier for removal. Small changes – but excellent design.

    [​IMG] [​IMG] [​IMG]
    Rear viewComparison with original F9Comparison with original F9

    The SE cable has a control unit on the right side which hangs just about equal with my jaw if worn cable down (so ideal height for the mic). The on-cable controls are designed to work with Android devices and do so brilliantly with FiiO's X1ii, X3iii, X5iii and X711 devices, allowing play/pause (one push), next track (two pushes), and previous track (three pushes). The volume control rocker also works. The microphone is crystal clear for calls (with my iPhone SE), as is the audio. I also tried the F9 with my wife's Galaxy, and everything worked as it should.

    Below this (about mid-chest) is a small tubular y-split with good relief below the split, but no relief above it. Y splits tend to be a little more forgiving in terms of wear, so no real issues with this. The jack is gold plated, 4 pole (for the in-line controls) and right angled. It has a small shoulder which allows perfect mating to my iPhone without having to worry about the case being an issue. It also has very good strain relief. The balanced cable is a very soft and pliable twisted pair, and FiiO tells us it is silver plated OFC. There are the same formed ear-loops and this time a 2.5mm balanced jack.

    [​IMG] [​IMG] [​IMG]
    ConnectorsSingle-ended cableBalanced cable

    Both cables have a very “Dunu like” rubber cable tie intact with the cable – the same as that used on their other IEMs and pretty much all of Dunu's releases now. This is a really simple mechanism that is unobtrusive - but means that whenever it's time to store the IEMs, the cable is always tidily looped. This remains one of the most simple, yet practical, methods of cable ties I have ever seen.


    I'll start with the easy one (isolation), and we can then look at fit and comfort. Isolation will be a little dependent on tip selection, and if you get a good seal, it is slightly above average for a hybrid with a dynamic driver. It is pretty good for most situations, but as soon as things start getting too noisy (public or air transport etc), you may find yourself wanting something with a little more isolation. The F9 Pro are designed to be worn cable up. Fit and comfort is exemplary – especially with the formed loops.

    [​IMG] [​IMG]
    Most tips fit pretty wellAnd the F9 Pro are very comfortable

    I have one ear canal slightly different to the other one (my right is very slightly smaller) - so I tend to find that usually single silicon flanges don't seal overly well. This is often even more of an issue with shallow fitting IEMs. Because the F9 Pro has a nice nozzle lip, I had no issues fitting any of my tips, and had great success with Ostry’s blue and black tuning tips, Sony Isolation tips, Spin-fits, and also Spiral Dots. The included tips were also pretty good, but I settled with what suits me best, and in the end I've been using either Sony Isolation, stretched Olives or Symbio Mandarins.

    The FiiO F9 Pros sit nicely flush with my outer ear, and are extremely comfortable to lie down with. I've slept with them often, and have had no discomfort on waking. The combo of the in-line controls with a FiiO DAP makes them brilliant for late night.

    So how do they sound?


    The following is what I hear from the FiiO F9 Pro. YMMV – and probably will – as my tastes are likely different to yours (read the preamble I gave earlier for a baseline). Most of the testing at this point (unless otherwise stated) was done with my X7ii, no EQ, and Sony Isolation tips. I used the X7ii simply because paired they not only gave me a very transparent window to the music with low impedance, and more than enough power – but also allowed me to use the balanced option. There was no EQ engaged.

    For the record – on most tracks, the volume level on the X7ii (paired with AM3a) was around 30-35 Single-Ended or 45-50/120 Balanced (on low gain) which was giving me an average SPL around 65-75 dB. Tracks used were across a variety of genres – and can be viewed in this list http://www.head-fi.org/a/brookos-test-tracks.


    • Sub-bass – good extension, nice audible rumble, balanced with rest of spectrum and doesn't over-power.
    • Mid-bass – very slightly elevated almost like an HD600. Sounds natural and gives good impact without masking the mid-range.
    • Lower mid-range – slightly recessed compared to bass and upper treble, but not enough to make vocals distant. Male and female vocal fundamentals are really good – rich and full.
    • Upper mid-range – elevated compared to lower mid-range, and there is a very even rise from 1 kHz to the first peak at just over 2kHz. Cohesive transition from lower to upper-mids, and very good euphony for female vocals.
    • Lower treble has a nice balance throughout, and a peak at ~8-9 kHz. There is extremely good detail with this tuning, and what surprised me was the excellent way it handled both cymbal strikes and also the subsequent decay. There might be the slightest bit of heat there, but nothing I feel an overwhelming urge to EQ out (although there is very occasional sibilance present).
    • Upper treble rolls off like most headphones from about 14 kHz onward – but enough extension to provide “air”.
    Resolution / Detail / Clarity
    • Clarity overall is stunning. Upper mids and lower treble have enough emphasis to give guitars bite and definition. Micro details are very evident.
    • Cymbal hits have a lot of clarity and presence but unlike the original F9, this time they are clearer without being brash or brittle, and the decay is really excellent. Brushed cymbal stokes (jazz) are also wonderful.
    Sound-stage, Imaging
    • Directional queues are good without being over emphasised. Presentation of stage is mostly just on the periphery of my head space with binaural tracks, but the violin in Tundra does sit outside (nice portrayal of width).
    • Very close to circular sense of sound-staging – with very slightly more lateral L/R leaning, but the impression of depth is extremely good.
    • With the applause section of “Dante's Prayer”, the FiiO F9 Pro shows an excellent sense of immersion (the sound of the audience flowing around me), and this time the overall impression was of more realism than the original F9 delivered. “Let it Rain” is usually my next track to listen to and it gave a nice 3 dimensional feel (the way it is miked). Guitar is crisp and clear. There was the usual amount of sibilance with Amanda's vocals – and it should be there because its in the recording – and again this time the F9 Pro is making a better job of not accentuating it.
    • Overall clarity and balance of the signature.
    • Very good sense of stage and imaging
    • Really nice cohesion with lower and upper register vocals
    • Great for both female and male vocals and with enough bass warmth to stop things being too dry or sterile.
    • The 8-9 kHz accentuation may be slightly uncomfortable for some if you're not a treble lover.
    • Occasional sibilance accentuation for me – but its only just there.

    The FiiO F9 Pro doesn’t need amplification for overall volume – and because its impedance isn't overly low, any source with an output impedance of less than 3 ohms should pair OK.

    [​IMG] [​IMG]
    Great with any sourceNo extra amplification required

    With my iPhone SE around 35-45% volume is more than enough with most tracks, and the FiiOs are generally at around 45-50/120. I tried the F9 Pro with the Q1ii, A5, HVA and a really nice little amp from XRK (which I’ll be reviewing soon). None of them seemed to be adding anything to my listening set-up other than some extra bulk. The A5 was really overkill, and I had to be careful to use variable line-out to get a usable volume (for my quieter listening tastes).

    This was harder for me than with the original F9 – simply because I really enjoy the default signature. I added some extra sub-bass via the Q1ii's bass boost, and while the F9 Pro responded with no distortion or clipping, for my tastes it just sounded a bit woolly and warm. I also tried trimming a few dB off at 8 kHz using the X7ii's EQ. It definitely slightly smoothed the upper end, and did remove the very little sibilance I sometimes experienced. Overall I'm actually OK with the default tuning. Either way the F9 Pro seems to respond well to EQ. I'm just not sure if many people will need to utilise it.

    I measured these, and there was no difference with the X7ii's AM3a amplifier module apart from volume. Even the slight change in impedance wasn't enough to change the overall frequency response. I'm not a great believer in the adage that balanced makes a huge difference. Yes, if the implementation is vastly different you can sometimes notice a difference, but more often than not the changes to cross-talk are already below the audible barrier, and most modern set-ups don't have crosstalk issues anyway. There was no difference perceptible to me once I'd volume matched. I knew I'd get questioned on it, so I utilised the Q1ii and took 2 readings – balanced and single-ended. I then volume matched (exactly a 6 dB difference), and what do you know – no frequency change. Its nice to have the option – but sonically I don't hear any benefits. If you volume match properly, I doubt you will either.



    These comparisons were all done with the X7ii, (no EQ) – and volume matched using a calibrated SPL meter and fixed 1kHz test tone first. Because I already knew how good the F9 Pro sounded to me, I wanted to throw it up against the best in its price bracket. So I chose the F9 original, Simgot EN700 Pro, Brainwavz B400 and my benchmark – the Alclair Curve.

    FiiO F9 Pro (~USD 139) vs FiiO F9 Original (~USD 99)

    [​IMG] [​IMG]
    FiiO F9 Pro and FiiO F9Comparative frequency response

    We can make this one pretty short. As far as build and design goes, they are practically identical – size material etc. The cosmetic changes introduced on the Pro are pretty good – knurling on the cable socket housing, colour coding for L/R, different angle on the cable exit (friendlier to after-market cables), and of course the Pro has the very good carry pouch and also the extra tip selection. Both have similar isolation (reasonable for a hybrid) and both are extremely comfortable.

    Of course the real difference is with the change of BA dual driver (F9 Pro utilises a Knowles dual BA set-up). As you'll see from the graph, the bass remains identical, and the tuning is practically the same except for the Pro having just a touch more upper midrange, and the lower treble peak being pushed back a little. The sound is very, very similar – with the F9 Pro having a subtly more engaging mid-range, and a little less troubling lower treble peak. The interesting test for me was using a splitter, and listening to the left ear-piece of the F9 original with right ear-piece of the F9 Pro. The differences were noticeable for about the first 30 seconds, and then as my ears adjusted, I may as well have been listening to a single stereo pair.

    Is the upgrade worth it? For the extra accessories, the minor design changes, and the subtle changes to sound – I think it is. But don't expect a big change. If I had the original F9 and was happy with it, I'd probably pass on the Pro. But if you're looking to get a little closer to perfection on a budget, the F9 Pro is definitely on my recommended list!

    FiiO F9 Pro (~USD 139) vs Simgot EN700 Pro (~USD 150)

    [​IMG] [​IMG]
    FiiO F9 Pro and Simgot EN700 ProComparative frequency response

    The EN700 Pro from Simgot Audio is one of my favourite IEM's in the sub $150 bracket. It hasn't been out that long – but it is an incredible example of how far the industry has come in the last few years.

    Both the F9 Pro and EN700 Pro have extremely ergonomic builds, solid builds and quality cables. With the F9 Pro you get the extra balanced cable, but with the EN700 Pro you get slightly better quality on the SE cable (along with 2 pin connectors which I prefer). Both have great design, good accessories, and reasonable isolation. More importantly both are incredibly comfortable to wear.

    Sonically they are very similar in the bass although the EN700 Pro may have just a little more warmth. Both have excellent mid-ranges, and the real difference in the mid-range is the lower treble – where the F9 Pro is a little cooler and brighter. The EN700 Pro is warmer and smoother in comparison.

    This one for me is a tie, and really comes down to individual preference.

    FiiO F9 Pro (~USD 139) vs Brainwavz B400 (~USD 180-220)

    [​IMG] [​IMG]
    FiiO F9 Pro and Brainwavz B400Comparative frequency response

    Brainwavz came from nowhere with the B400, and knocked it out of the park IMO. A quad BA in a very ergonomic housing, and spectacular tuning. Compared to the F9 Pro, I'd call design and ergonomics a tie, the F9 Pro pulls slightly ahead with the more permanent materials and overall finish quality. But we are splitting hairs here – both are truly well designed, well built, and extremely comfortable monitors.

    The difference here is in the tuning, with the B400 opting for a much flatter overall signature with a smoother upper end – whilst still retaining very good extension. Both are exceptionally clear and clean sounding. Because the B400 has less lower treble and upper-mid emphasis, it has the tendency to sound a little warmer overall, with the F9 Pro again sounding cooler and brighter. The interesting thing is the bass though. I love the B400's speed, but there is something alluring about a well tuned dynamic driver, and the F9 Pro somehow manages to get this absolutely spot on in comparison. Again – both are exceptional monitors and will come down to preference. I might lean slightly toward the F9 Pro in this comparison – but simply because of my own preference for a slightly brighter and cooler monitor.

    FiiO F9 Pro (~USD 139) vs Alclair Curve (~USD 249)

    [​IMG] [​IMG]
    FiiO F9 Pro and Alclair CurveComparative frequency response

    I know this is getting a little out of the F9 Pro's depth, but what happens when I put it against one of my favourites in the sub $250 bracket? The Alclair Curve is the most ergonomic IEM I own (and yes this one I do own). Both IEMs have fantastic build quality – with the F9 Pro's shell being alloy vs the plastic/acrylic shell of the Curve. Both have replaceable cables. Both have exceptional comfort. The F9 Pro of course has the balanced cable option – the Curve isolates much better.

    Sonically these two have similar overall signatures. Linear well extended bass, nice balance overall, a bump in the mid-range, peaks in the lower treble. The main difference is that the Curve has a flatter overall signature, where the F9 Pro is more coloured (especially in the upper mids and lower treble). The F9 Pro is not embarrassed at all in this company. For me personally – I'd still pay the extra and take the Curve for most music, but there is definitely some tracks (especially acoustic guitar with vocals) where the F9 Pro's coloured mid-range simply shines. The F9 shows incredible value for money – and that’s why I chose this particular comparison.


    By now you'll already know where I see the strengths of the F9 Pro like the original F9, the one massive strength is in perceived value. With the F9 Pro its simply off the charts. This is an IEM which can comfortably go toe to toe with IEMs at much higher prices. While it doesn't necessarily set a new bench-mark in quality/price ratio, it comfortably lives alongside the best in its price bracket (and in the bracket above it).

    If these were on the market when I was originally looking to buy a higher end pair of IEMs (I eventually started with the Shure SE425 and later the SE535), I doubt I would have spent the money I did. For a budget set-up (which doesn't sound budget), I can't think of too many which would beat it.


    FiiO has really pulled out some surprises with their IEM releases this year and the tweaks in the F9 Pro show the maturity FiiO is already reaching – even as a comparative newcomer to IEMs. The F9 Pro is a serious contender at a low price (almost entry point for some).

    It combines good build and design, great ergonomics, and well thought out accessories, with an exceptionally mature and balanced signature. If you're sensitive to treble (especially at 8-9 kHz), or dislike a cooler brighter overall signature, then it may not be for you. But if like me you appreciate overall balance, with a mid-forward signature, and a cool clean and detailed presentation, you are in for a real treat. If you prefer the signature, but find it a little overdone, a drop on the 8 kHz EQ slider of about -3 dB is a really quick fix.

    I put these through my new objective ranking calculation module, and unsurprisingly they scored incredibly well. I would unreservedly recommend the F9 Pro. In this price range, its going to be hard to beat.

    Scoring Chart
    HeadphonesFiiO F9 Pro (out of 10)
    My ScoreOut Of WeightingWeighted Score
    Sound Quality
    Bass Quality8.5108.00%0.68
    Mid-range Quality8.5108.00%0.68
    Treble Quality8108.00%0.64
    Overall Tonality8.5108.00%0.68

      Copland62, FiiO, pipopl and 28 others like this.


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