Fiio is back with its successor to its hit FD5 earphones from 2021: the Fiio FD15. They’re a surprising successor, coming in at around half the price but offering surprisingly competitive sound with a cohesiveness that only a single dynamic driver can deliver. Just don’t go in expecting massive bass.
Specifications
Current Price: $149.99 (AliExpress)
Fiio FD15 - First Impressions and Key Features
The Fiio FD15 is the successor to the FD5, an in-ear monitor I very much enjoyed back in 2021. So much so, It’s part of my normal rotation of earphones even though my collection is quickly approaching triple digits. The FD15 takes a different approach to the single dynamic driver concept — the most tried and true in all of personal audio — retaining the DNA of the FD5 but pushing things in a different, more accessible direction.
Like the FD5, the FD15 is designed for audio enthusiasts but unlike that set, which retailed for $300, the FD15 will only set you back $150 and offers a premium fit and finish and impressive acoustics. There are some areas where it’s clear that Fiio scaled back to offer a lower price, but there’s enough here to make it feel like a very good value at the end of the day.
Starting with the unboxing experience, we have a cardboard box that shows a close-up of the earphones and opens magnetically to reveal the real thing within. The earpieces are on display within foam cutouts while the accessories are hidden inside of a cardboard sleeve in another compartment. While it’s not the fanciest unboxing experience, at this price, it’s on par with what you would expect, and I would rather Fiio invest more in the buds themselves than a box that will be thrown away the same day it’s opened.
In usual Fiio fashion, there’s a generous assortment of accessories. Like the FA19, we have a wide range of ear tips sorted by their sound characteristics: Bass, Vocals, and Balanced. Fiio also includes small, medium, and large pairs of its own premium HS18 silicone tips, as well as two pairs of soft foam tips for the best isolation. I went with the HS18s, which are exceptionally soft and fit my ears well.
Inside, you’ll also find a high quality cable. It’s made of monocrystalline silver and silver-plated copper and is woven from four strands of 120 wires each. It uses a polished metal sleeve for its modular end and Y-splitter and protective resin shielding for its MMCX adapters. It’s a touch stiff thanks to all those wires but isn’t prone to tangling and doesn’t hinder its performance at all. The terminating end comes with both 4.4mm balanced and 3.5mm single-ended jacks that can be swapped out by unscrewing the sleeve surround in and unplugging/replugging the new termination in.
The FD15 also supports swappable sound nozzles to customize the sound. There’s a black-ringed set that comes pre-installed and a red-ringed set on a tab within the box. The black set delivers a neutral sound while the red set delivers more bass. It’s a noticeable difference. While it doesn’t completely change the sound of the IEMs, the red-ring set definitely provides more body to the listening experience.
The case is the same we’ve seen on other more affordable sets: clear plastic with a slide out drawer. And odd Lego pegs on the top and bottom. It’s just a case but the Lego pegs make it seem a bit childish to me. But hey, if you have Lego, build away.
The IEMs themselves are very reminiscent of the FD5. They’re made of polished metal and have the same circular shape. Instead of the semi-open back design featured there, the FD15 is completely closed and instead focuses on innovating internally.
The dynamic driver is massive by earphone standards. At 13.8mm, it has 40% more surface area than the FD5, allowing it to move more air and perform more efficiently. The driver uses a combination of magnesium and aluminum for its diaphragm, a composition Fiio calls Magnalium. It’s not something I’ve seen elsewhere but the company says that it’s able to offer exceptional hardness and low distortion. This is paired with a diamond-like carbon (DLC) outer ring to promote a natural, clear sound signature.
Apart from the driver itself, Fiio has incorporated a number of innovative systems to ensure a competitive sound with the FD5 — a sound that Fiio reckons is actually better in most ways. For the bass, it features a tesla valve system to modify air flow and resistance on its way toward the nozzle, adjusting resonances for deep, detailed reproduction. For the mids, it has a longer voice coil and more powerful magnet to push the Magnalium driver and DLC gasket system. Finally, the highs are accentuated by the frontal shape of the driver which dips and then rises in the center to create a W shape that increases the total vibrating area of the speaker and enhances its higher frequencies.
Or so says, Fiio. In the above picture, you can see the company’s own assessment of how the two compare. My own impressions are slightly different but it’s enlightening to see how they compare and the impact a difference in ears can make.
Fiio FA15 - Listening Impressions
Graph Credit: Audio Reviews News via Squig.Link
The Fiio FD15 is not a difficult set of IEMs to drive. An Apple headphone adapter will work fine, though like the FD5, they benefit from some volume headroom. I conducted my testing using a mix of the Fiio M23 and the Fiio K9 Pro ESS.
As I mentioned earlier in the review, the set comes with an interchangeable nozzle system that makes an impact on the sound. As you can see in the graph above, courtesy of Audio Reviews News via Squig.Link, the red, or bass, filter accomplishes its warmer sound by slightly rolling back the upper mids and treble. The difference looks very slight when graphed but it’s audible and will allow you to tailor the sound a bit without the need for EQ.
Bass: After reading so much in the marketing about the FD15’s achievements in the low-end, I was relatively surprised to find that my first listen was actually quite balanced. Perhaps a touch warm, and though the quality of the bass was good, the quantity wasn’t where I expected it to be based on the marketing. The default nozzles are the culprit here and lend the set a more neutral, balanced sound profile, yet not one without nuance. Though quieter, the bass is fast and responsive and has good extension into the rumble frequencies. The black nozzle is not a good fit for hip hop or other bass heavy genres but for live tracks, acoustic recordings, and classical music, it’s very fitting and sounds quite good.
Swapping to the red nozzle doesn’t change the character of the bass. It’s still fast and reasonably detailed (planar IEMs offer more texture to the sound), but there is more of it. The sound begins to tilt more in the direction of warmth and full bodiedness. It’s not overwhelming and, like the FD5, this just isn’t a set for bassheads, but it opens the door to more genres and offers a more mainstream sound. Don’t sleep on the nozzles! They actually matter here.
Mids: The mids are the high point for me. Vocals are smooth and forward, coming right to the front of the mix. Depending on the nozzle you use, they’ll cater more to male (red) or female (black) voices, but vocalists definitely shine. The detail in the mid-range, similar to the bass, doesn’t offer the same level of granularity and crispness and a planar of hybrid but it makes up for it with a cohesiveness and isn’t what I would consider lacking, per se. It’s a flavor of sound and if you’re not A/Bing or coming from one of those other types of IEMs, it’s likely you won’t see much lacking.
The rise in the upper mids and mountain range treble region allow the harmonics of guitars and other stringed instruments to come out and give brass a pleasantly crisp timbre. These instruments sit behind singers in the mix. Instruments sound good but it seems clear that this is a vocals first pair of monitors.
Treble: The treble is bright and sparkly, though the lower treble sounds tempered to reduce harshness. It can still be a bit bright at higher volumes but this tuning brings energy to the sound. Cymbals and hi-hats cut through but don’t jump to the front like some sets. Instead, they sit in the middle, alongside the other instruments so vocals can remain center-stage. Overall, I think the treble is well done, though a touch more tempering may still be in order for a future version.
Technical Performance, Soundstage, and Imaging: Despite being completely closed back, their soundstage is reasonably big. The width seems to extend just outside the head and there’s a moderate amount of depth so you can discern the different layers of sound. These layers are not stretched out like we sometimes find with hybrids and planars but you can hear them well enough that you’ll be able to pick out the different elements that make up your song or game. The FD15 also offers strong stereo imaging, enhancing their imaging and positionality.
Gaming: The FD15 works for gaming and will allow you to hear everything well enough to remain competitive or immersed, depending on your genre. The red nozzles provide just enough bass to be immersive and engaging, capturing some of the visceral action of first person shooters and the grandiosity of a final dungeon or raid boss. The power of the rumble is a bit lacking for very intense moments, however, and the mid-range tuning emphasizes voices (team callouts and Discord calls) over footsteps, so while you’ll pick up on them most of the time, their positioning can sometimes get muddy if there’s a lot going on. I would recommend using Dolby Atmos with this set if you plan to play games with it.
Overall Impressions and Final Thoughts
At $150, the Fiio FD15 is a good value for music. They’re extremely reminiscent of the FD5 in construction and the big picture of their sound, which immediately makes their price point all the more appealing. For gaming, they get the job done but wouldn’t be my first choice since it’s clear that they’re intended to highlight singers which may not mesh well with certain types of games. For music, however, their balanced to warm-balanced sound is very enjoyable and well worth trying for yourself.
The product described in this article was provided by the manufacturer for evaluation purposes.
