So, FiiO kindly shared a FX15 a few weeks ago and I have been listening to it while working so roughly 5-6 hours daily and comparing it with the other IEM's in my collection (some moondrops, Kiwi ears, Salnotes and the Truthear Zero Red), so I thought I would share my thoughts on this IEM.
What is in the box:
The FX15 comes with a lovely box and a great set of accessories. The presentation of the IEM would be perfect for Valentines days
:
The number of accessories within the box is also great:
The Cable especially is exceptional quality and I love the 3.5mm and 4.4mm connections on the cable.
The Eartips selection is also great - these are the main way FiiO want you to tune the sound (rather than the A/B Switch but more on the switch later), you can see recommendations in this photo:
I love the slightly smokey look to the shell, though I am not fan of the pattern on the IEM its fine. Here are a couple of close ups:
Here is the size compared to the Truthear Zero Red:
You can see the slightly 'opinated' shape compared to the truthear and I liked it - the 'ridge' in the shape fitted my ears perfectly - though that will obviously be very subjective.
Overall I you get a very premium feel from this IEM (and you should at the price) but the real star of the show with this IEM is the EST drivers - 4 per ear together with 1 DD for the bass and a single BA for the midrange. So lets get onto the sound signature.
Sound Signature
The FX15 has a slight V-shaped signature (not a bad thing but probably not what I had been using in recent months) so it took a few days to get use to the sound, it was great (until I switch between different IEM's but more on this later). So I started my initial listening with a playlist with some 'challenging' test tracks which I thought would give me a true taste of what the 4 x EST could provide and I was not disappointed. So typical test tracks like Bjork Hunter and James Blake Limit to your Love sounded great both in bass but especially with the treble (the best I have heard I would say), I quickly settled on listening to a selection of EDM and nicely produced but 'challenging' albums like Billie Eilish debut, I also tried a series of percussive tracks where ones like Tool 's Chocolate Chip Trip and Earth Drum's by He Xun-Tian really stood out - all these were perfect matches for this IEM. I would totally recommend the default tuning on this IEM with this type of music.
But it's not all great, switching back to a more normal selection of music I did found something didn't sound right on some songs, e.g. Tracy Chapman Fast Car had a little too much bass for my liking and some tracks on Portishead Debut Album were just too much (e.g. Pedestal), I then spend a day or so switching between the FX15 and some harman tuned IEM's like the Moondrop Variations and the Truthear Zero Red (both with the Bass adapter and without) and trying to decide which I liked most with what tracks. It was very close but I did feel that the midrange on the FX15 could do with some slight adjusts in the mid-range for maybe 30% of the tracks.
I then asked FiiO could I get some measurements which they provided so I decided to graph that data with some comparisons in REW and this was very interesting, mainly because it graphed much 'worse' than it sounded - I was expecting a small increase in bass and maybe a 1db dip in the midrange (or similar) but this was the comparison graph:
Note: These are BK-5128 'raw' measurements provided by FiiO and compared with RAW measurements from the Moondrop Variation data and the Truthear Zero Red data comes from Crinkle recent BK-5128 measurements from his website
https://www.crinacle.com
I then decided to see what would happen if I fixed the midrange with EQ so I lowered the mid-range and increased the mid-range to be closer to the other 2 IEM's I did not touch the Sub-Bass or the treble region and spent a few more days with the FX15 and for me this fixed the sound of this IEM for almost all types of music, obviously this is very subjective, but what I wanted from this IEM was the exceptional EST treble and the nice quality DD drivers providing excellent bass but I believe the midrange BA does need these tweaks to become a daily driver. But the default tuning does make a great experience for certain types of music as I hope I have indicated.
For those interested in a little more technical detail and some graphs I created post on ASR with more data and some of the technical details FiiO shared with me:
ASR post about the FX15
The A/B switch:
Finally a little details on the A/B switch - effectively this turns off the EST drivers and leave the single BA driver providing everything other than the Bass, other than a quick 'demo' when I first tried the IEM, I did not find it useful. It was also hard to switch, FiiO provide a 'tool' on the handle of the brush to switch it but I could not switch it easily when wearing the FX15 - maybe someone else could assist you in a A/B 'blind test' with this switch but it seems strange - options and after a hour or so I did not bother with the switch and left it in the on position.
Summary
FiiO new flagship IEM the FX15 has exceptional Treble response (I won't call it 'technicalities' though I believe most reviewers will call it that) and when balanced with the excellent bass this IEM provides it sounds fantastic with certain types of music, but with more mid-range focused music I think a little EQ can provide a more rounded experience. With those little midrange EQ tweaks I found the FX15 to be the best sounding IEM in my collection.