FiiO

FX15 Tribrid Universal In-Ear Monitors

£699.99 RRP

FiiO’s product lineup is always jam-packed with new releases every year, and we’ve finally got the brand’s first-ever in-ear monitor that uses electrostatic drivers in addition to the more common dynamic and balanced armature drivers, resulting in a so-called ‘tribrid’ offering. 

And if you’re not so keen on the electrostatic sound, the FX15 has a hidden trick up its sleeve, allowing you to turn off the electrostatic driver to run the IEM on just the dynamic and balanced armature drivers. We’ll talk more about that later…

UP CLOSE

The earbuds themselves are expertly built, as expected of a FiiO product. Made with 3D-printed resin, the shells are smooth and free from any seams or rough edges that might cause issues with comfort while being worn. Indeed, the fit is incredibly snug and comfortable in the ear; I had no problems even after the entirety of a seven-hour flight. 

On the faceplate, there are interlocking ginkgo leaves, which look absolutely gorgeous, although a golden yellow colour might be nicer compared to the pinkish colour FiiO has gone for. Moving to the rear of the shells, there’s a switch that allows for the electrostatic drivers to be turned on or off, although it’s a bit of a puzzle as to why someone would buy a special electrostatic IEM design just to turn its fancy drivers off!

The body of the shell is made with a smoky translucent resin that lets you peek into the IEM and take a closer look at the four Sonion electrostatic drivers, a 10mm DLC dynamic driver and a Knowles balanced armature driver, all of which are neatly arranged and look lovely. 

In the box, FiiO also provides a plethora of accessories, with five kinds of tips (vocals, bass, bi-flange, balanced and memory foam) in a hard-sided case, along with two additional packages for FiiO’s own HS18 tips as well as SpinFit tips, which I preferred above all the rest. Thanks to the semi-custom shape of the shell and the tips, the passive noise isolation out of the FX15 is very decent, with the bulk of environmental noises blocked out despite the air vent for the dynamic driver. For even better noise isolation, the foam tips included will do an excellent job.

There’s also a nice looking carrying case included, with a leather and suede exterior that contains a few different tools, such as an MMCX removal tool alongside a cleaning brush and the 4.4mm interchangeable jack that FiiO has opted for over the years. This time, there’s no 2.5mm jack, just the standard 3.5mm and 4.4mm options that can be swapped out via a twist-lock system. Regardless, it’s a neater and more elegant option than using adaptors. 

The cable is an eight-strand silver cable with Litz braiding, all enclosed in a TPU sheath that’s robust and doesn’t have any wire memory – so it straightens out easily rather than remembering kinks and curls. The expanded MMCX connectors are incredibly snug and don’t allow for any unwanted swivelling, which is great. Unfortunately, it does mean that removal is a bit tough with bare hands, so it’s a good thing that FiiO has included the MMCX removal tool to help if one wants to cable swap.

With a quoted 24 ohm impedance and 103dB/mW sensitivity, the FX15 is relatively easy to drive; I found that it paired very well with the FiiO Q3 and even worked decently when plugged directly into a laptop. However, I would recommend that these earbuds be paired with a warmer source for better tonal matching, compared to something more analytical.

THE LISTENING

FiiO’s FX15 is an absolute delight for people who prefer a balanced sound with a touch of emphasis on the treble. Thanks to those four electrostatic drivers handling the highs, the upper registers are a little brighter and crisper than a standard hybrid in-ear monitor with dynamic and balanced armature drivers. Having previously heard some of the company’s other IEM offerings, like the FH5S, I daresay that the FX15 is one of the brighter models with a V-shaped signature, which I do enjoy quite a bit.

There is a touch of warmth in the bass, which is handled relatively well by the 10mm driver; this results in a thick, full-bodied slam while not getting too overwhelming. There is plenty to enjoy here, and it should satisfy most listeners except for the more extreme bassheads out there. Low bass is also very well done, being quick and responsive with plenty of texture. 

As for the mids, while there’s a good amount of detail and accuracy, it does feel that the single-balanced armature driver struggles at times, working hard to try and deliver optimum performance. Don’t get me wrong, it does this admirably, but the upper mids get a bit shouty from time to time; vocals in this region can sound forward, although that’s not always a bad thing. Listening to Fall Out Boy’s Sugar, We’re Goin' Down was a pleasure, with Patrick Stump and Joe Trohman’s guitars still clear in the background contrasted against the deep, thumpy drumbeats and Pete Wentz’s chunky bass guitar. 

Treble performance is what you would really consider buying these in-ear monitors for. It is quite gorgeous, with plenty of sparkle and energy and oh-so-much space and airiness for instruments to show off fully; there’s plenty of detail and excellent resolution of the most nuanced aspects of the recording. The electrostatic drivers shine in this respect – and if you purchase this product, then it is most likely because you know that you’ll enjoy this sort of sound. For those more sensitive to treble, this IEM might not have so much appeal because of how energetic it is. Yet it can certainly be tamed slightly by swapping for a copper cable, using a warmer source or playing around with ear tip choices to try and damp down the high frequencies a little. Personally, I love a bright and sparkly top end, so the FX15 is right up my alley!

Soundstaging is also magnificently done, with a wide recorded acoustic that offers plenty of air and space between individual instruments and vocals. This makes for a more detailed rendition of complex or dense tracks than you would normally get with other earphones. A great opportunity to see how these earphones deal with complex tracks was during the chorus of Sucker by Jonas Brothers. Here, the percussion, claps, guitar strums and drums all separated well but still played along nicely together, while vocals were accurately placed in the soundstage.

THE VERDICT 

There is so much transparency and detail on offer from FiiO’s FX15 that it’s hard to believe its modest pricing. It’s nowhere in the vicinity of ‘cheap’, yet compared to the price of other electrostatic IEMs, it’s more of a bargain than you might think. Indeed, I reckon it’s a fantastic first attempt at an electrostatic offering by FiiO, and the company should be proud of itself for releasing such a capable product at such a keen price. 

I found the sound so much to my liking that I am considering picking up a pair to replace my usual balanced armature choices. We’ll keep a close eye on how the electrostatic IEM offerings in the market develop, but the future certainly looks bright right now. 

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