FiiO FD15

Full Review Here

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Fiio FD15 Review​

Intro​

Hello, this is my full written review and feature of the Fiio FD15 ($149) from the audio brand Fiio. The FD15 is a gorgeous single dynamic driver earphone which acts as the predecessor to the legendary Fiio FD5 (originally $300) from years past. Folks, the FD5 still holds up, even today. Truly a special iem and one that I’ve enjoyed since its inception. Such a fun sound, musical, heavy bass, sparkly highs and a build and design which is to die for. I’m telling you, the FD5 is still one of the best built and best looking iems anywhere near its price point (Subjectively speaking of course). I actually purchased the FD15 for right around $147 off of Amazon US as I absolutely needed to hear this set! Also, the price is so low as opposed to the older FD5 that… I couldn’t resist.

Fiio​

Fiio is one of those brands that absolutely stole my attention for years. I’ve been a fan ever since some of their older sets like the Fiio F9 and F9 Pro. I’ve only actually reviewed a handful of their products over the years. Those include the Fiio FH5 (FH5 Review), the Fiio FH15 (FH15 Review), the Fiio JD7 (JD7 Review), the Fiio FH9 (FH9 Review), their wonderful true wireless set, the Fiio FW5 (FW5 Review) and finally one of my favorite amp/dacs under $500, the Fiio Q15 (Q15 Review). Each product I gave solid marks. In fact, the FH9 is still one of the best iems that my ears have heard under $1k. Truly a special set. The JD7 I still regard in my top five under $100 for a single DD. It’s an absolute beast which flew way under the radar. Even their tws set, the FW5, I challenge you to find a better “sounding” tws anywhere near its price. It has an AK dac chip inside of it for crying out loud. Just awesome products. Beyond those I’ve reviewed, I’ve purchased so many that I’m sure I’ve paid for someone’s college at Fiio.

Staying Power​

This is a brand which has been around since 2007 when they were heavily into dac/amps and portable audio products. Obviously, their catalog has evolved to darn near every type of audio product on the market. I feel that price to performance, good build quality, and always a focus to use the best materials ie: dac chips, drivers, amping etc. Have they had some bombs? Of course they have. Sure, they’ve had some duds over the years. However, for the most part Fiio has been a huge player in the audio game with just about every product that they bring to market. Also, they have some serious staying power. Ask yourself how many brands have been around since 2007 while staying relevant the entire way through. I can actually answer for you… there aren’t many.

Competition ​

Now, as always, the one huge dilemma for any product in darn-near every price segment is “competition”. No doubt the FD15 is up against some heavy hitters. Think about it, the Simgot SuperMix 4 (SM4 Review), QOA Adonis New (Adonis New Review), Hidizs MP145 (MP145 Review), Hidizs MP143 (MP143 Review), Juzear 41T, CCA Hydro (Hydro Review), Aful MagicOne (MagicOne Review), Sliivo SL41 MK2, QOA Aviation (Aviation Review), and remember there are a multitude of iems hovering around $200 that are absolute killers. Also, I only named a few there. Tack in about fifty more to that total of iems that seriously compete for your dollar. So, the FD15 is not without an uphill climb, and it definitely needs to stand out in one way or another. I certainly have an idea of where I feel that it stands and possibly who the FD15 is for, and I’ll try my best to explain my thoughts as you go along in this review. Also, just a side note; when I rate the FD15 later in this review it will not be against all driver configurations, but instead against single DD sets within its price point. Anyways, I’m definitely ready to get into this. So, without further ado, the Fiio FD15 everyone…

Gear used for testing​

–Ifi Go Blu

–EPZ TP50

–EPZ TP35

–Aful SnowyNight

–Shanling H0

–Fiio Q15

–iBasso DX240 with Amp8 MK2

–Shanling M6 Ultra

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Packaging / Accessories ​

Unboxing ​

A few things in life are “givens”. It’s a given that the sky is above our heads, that the ground is under our feet, and that peanut butter and jelly sandwiches are always better with crunchy peanut butter. Okay, I may have slid that last one in there. Now, there is one other “given” … that is… Fiio will always provide a nice unboxing experience. The question isn’t whether it will be good, but rather, how good? So, the FD15 arrived at my home fairly large white box with a picture of the FD15 on the cover and some specs on the back. It’s a harder style of cardboard, feels nice, opens from the top. Once opened you’ll see the FD15 looking all stellar with the cable attached tucked nicely inside some foam cut-outs. Next to the FD15’s is a smaller box which houses the carrying case (if you want to call it that). Inside of the case is all of the accessories. Right away you’ll see many little baggies (the worst baggies ever) which carry all of the different styles of eartips, the cleaning tool, the extra tuning nozzle, as well as the mmcx tool. Really a grand packaging and accessory haul for a $149 iem.

Eartips ​

As Fiio does, they added in five different styles of eartips and eleven pairs of eartips into the packaging. In case anyone hasn’t informed you… that’s a lot. The first set of tips are the “Balanced” tips (S, M, L) which are gray in color and come with a semi-wide bore, rigid flange and fairly rigid stem. Next Fiio provides the “Vocal” tips (S, M, L) which are a white flange & red stem wider bore eartips which have a slightly flimsy flange and a shallower fit. The next set is the “Bass” tips which have a light gray flange with a red stem which have a semi-wide bore, rigid stem and firm flange. These tips are very much like KBear 07 eartips. Great eartips that I seriously wonder why in the world they call them “Bass” tips. Anyways, next we have Fiio’s special “HS18” tips which are a white semi-wide bore eartip with a flimsy flange, flimsy stem too. I do not like these tips and have zero idea how they seal in anyone’s ears. Lastly, Fiio provides two sets of medium sized slow rise foam tips. Decent foamies but I never use foam unless I absolutely have to. Anyways, this is an awesome array of tips for a $149 set. I did use the “Bass” tips as they literally are the KBear 07’s yet just colored differently. Great tips for this set too as they enhance the upper mids by a small degree and add some crispness to the bass, maybe a hair more punch too.

Carrying Case​

So, the “carrying” case that comes equipped with the Fiio FD15 is the same case that came with the Fiio JH5. Ya know what, I have to change direction here because folks, this isn’t actually a carrying case at all. This is a drawer. But wait, there’s more. Not only is it a drawer, but it also has Lego pegs on it? I know, it’s confusing and an odd decision on Fiio’s part. Especially since they’ve literally used this exact drawer with many of their sets now. I don’t “not” like it. I actually don’t know what to think. Anyways, the case/drawer is a fully transparent rectangle that comes with a slide-out drawer. It’s of a decent size. Meaning, you could fit the earphones and cable as well as the rest of the accessories if you are talented at packing things. I think the benefit of these drawers is that you can put one on top of the other as you purchase Fiio gear. At least I think that was the vision. Now, I don’t know if it’s the best vision either. I know one thing is 100% true though, at least some of you will absolutely adore these case/drawers.

Cable​

Now we get to a truly positive aspect of the FD15, that is the cable. Fiio provides a very nice-looking wire with this set. It’s nicely plump, substantial, nice to look at and best of all, it’s modular. The cable is actually a Furukawa monocrystalline copper and Furukawa monocrystalline silver-plated copper cable. As pure as it gets. This cable is comprised of four large strands and each strand has 100 copper wires as well as 20 silver-plated copper wires. That makes a total of 480 wires with a total size of 22AWG. Fiio states that they heat treat all alloys to their melting point, up to 1050 degrees Celsius for around 744 hours. The cable is an mmcx cable with an almost metallic brown insulation. Truly a gorgeous cable folks. In fact, Fiio promotes this cable to be identical to their Fiio LC RC 2024 cable. Like I said, the FD15’s cable is a modular design, in that it comes with both 3.5 single ended and 4.4 balanced terminations. Very easy to swap too. All you do is align the termination with the cable, push it on, pull the cover back over it and thread it on. In my opinion the cable is a bright spot of this set and perfectly contrasts the stainless-steel design of the FD15. I love the color choice, the materials, as well as the modular aspect of this cable.

Full Review Here

Build / Design / Internals / Fit ​

Build Quality ​

So, do I even have to write this section out? I mean, this set is an absolute tank! So, the FD15 is made entirely out of 316L stainless steel. Really one of the hardiest steels out there, completely resistant to any corrosion. Also, stainless steel will give you some of the most gorgeous mirror polished designs. Especially 316 stainless. I know because I worked with 316 for many years. Fiio went through the painstaking process of electro-plating and hand polishing each unit, so they are striking to look at. Also, fingerprints love stainless. But I digress, back to the good stuff. Folks this set is so hardy, and ridiculously durable. The style is the same body of the Fiio JD7, FD5, FA7S, FD3 etc. Same mold, or at least very similar. It’s awesome. The only complaint back in the day was fitment for some folks. Fiio states that they remedied this problem by raising the y-axis of the nozzle 7.6-degrees. I never really had a fit issue in the past (so long as my tips were right) but this newer FD15 fits like a glove. Anyways, the nozzle really isn’t very deep for insertion and not what I’d consider shallow either, maybe medium length, and with the tuning nozzles attached they are exactly 6mm in width. Pretty standard. You have three tiny vents right in a row at the back of the unit and one small vent near the nozzle. Not much more to say other than to reiterate that the FD15 is built very well. Oh, and it has two sets of tuning nozzles.

Tuning Nozzles ​

Like I said, the Fiio FD15 comes equipped with two sets of tuning nozzles. I like these types of tuning nozzles the best. These are the longer style where the male threads are on the nozzle adapters and the female threads are on the shell body. They are longer and less easy to lose. I have to be totally honest; they don’t change or alter the sound a whole lot. You have the Black nozzle, which is supposed to enhance the highs, make them more detailed, a bit more levity to the sound. Next you have the Red Nozzle, which is supposed to be a bit lusher sounding, more low-end weight, more of an emotional organic sound. To be perfectly honest, yes there is a discernible difference, but it isn’t world changing. You won’t all of a sudden have a completely different set of earphones by changing the nozzles. Which, by the way is about par for the course as far as tuning nozzles goes. What you will have is a slightly altered version of the same tuning. Like, using the red nozzle I still hear a neutral sounding set. Perhaps the low-end is a hint more emphasized, but not by much. The treble is slightly less energetic which gives the perception that the bass has a hair more oomph. The black nozzle provides a hint more extension into the upper frequencies (it seems) while the bass perhaps doesn’t sound as well defined. I suppose I’d consider the black nozzle as the more likely approach with a better balance by the tiniest of margins. For review purposes I did use the black nozzle. Yet I honestly still enjoy the red.

Design​

Folks, I absolutely love the design. Of course, I’ve loved the design of every set from Fiio with this body style. You’ll notice a groove on the faceplate area which houses the Tesla Valve underneath which runs to the three small vent holes. Anyways, it creates a dope look. Again, fully stainless steel with a high polish makes the FD15 look very handsome, regal, and simply gorgeous. The FD15 comes in two colorways. Those being the silver set that you see in my pictures, and they also come in black, which is sweet looking in its own right. I don’t have a whole lot to say but I really am impressed. The FD15 looks slightly similar to the FD5 and really does rival it in the looks department. For me anyways.

Internals​

Now we get to one of the more loaded sections. Friends, this set has so much physical technology within. Like I stated, the FD15 comes equipped with a massive 1.5T tesla 13.8mm Magnalium Diaphragm DLC Dynamic Driver. Magnalium is a cute name to call it, but the material is actually a blending of magnesium and aluminum. Just by saying that you know that it is a very strong and efficient material with high rigidity and strength. Next, it’s the gasket which is made using the DLC material and now comes in a w-shape. Basically, the driver effectively provides an uptick in vibrational area by around 30% from the FD5. Which is very substantial. Next, the voice coil is actually 1.38 times longer resulting in what Fiio says is a 70% in driving power. Lastly, Fiio added what they refer to as a “Tesla Valve” which sits just under the faceplate and vents to the atmosphere through the three small vent holes on the rear of the unit. This Tesla Valve is really a channel with what appears to be restricted cavities as the pressure builds it’ll lower the resonant frequency and balance the pressure very well. External air flow into the FD15 passes unrestricted while internal air flows to the outer cavities along the tesla valve. Okay, I did a horrible job explaining that, but you get the gist. The tech is great as Fiio is quite literally always trying new things. I could go on and on with acoustic tech that they’ve employed in their past earphones. They are one of the few budget-oriented brands doing actual R&D and trying new things. Other than Aful and a few others. However, Fiio has so many patents. True engineers.

Fit / Comfort ​

Like I said, the fit for me is pretty nice. I have to fiddle for a second or two but once they are seated and sealed, they are comfortable. I would suggest that you get a few different types of tips to try out just in case the FD15 doesn’t fit perfect right away. However, the FD15 is an extremely comfortable set once you get them where you want them. Their weight really isn’t an issue either because of the fact that they sit inside of your outer ear.

Drivability / Pairings ​

Output Power ​

The Fiio FD15 is rated with an impedance of right around 32 ohms as well as a sensitivity of about 112 db’s. What this means is that the FD15 is a very sensitive iem. I have used everything from those super cheap no-name Amazon dongle dacs on 3.5 to my iPad and I have gotten good fidelity and plenty of headroom volume. Without question the FD15 can be used with smartphones, and weak dongle dacs. However, like most iems the FD15 is helped quite a lot with more juice. It has a huge 13.8 mm Dynamic Driver which seems to yearn to be pushed. In fact, the best I’ve heard from the FD15 is when I set high gain on my dongle dacs (too many to name) or medium gain on my 1w daps and dac/amps. Trust me, the FD15 will scale. However, there is a plateau where there is no further benefit with more power. I’d say that ideally you should try to give this driver a good 50-100 mw @32 if possible (best guess, don’t take my word for that). Just to push the driver a little bit. I noticed the bass region tightens up, becomes punchier, more contrast in the sound, better defined too. The treble seems to extend a hair further as well but that may be me dreaming that up, although… I really don’t think so. So, more juice helps but at the end of the day the FD15 can be driven from most any source with no issue whatsoever.

Source Tonality​

As far as pairing the FD15 I’d say that you can use pretty much any source tonality and be perfectly fine. I don’t think the neutrality of the FD15 sounds worse or better with a cooler or warmer source device. Just make sure you enjoy the sound of your source. Really, I think the neutral sound of the FD15 kind of goes with any source tonality. For instance, I used the neutral iBasso DX240 and I’m in love, sounds wonderful. Also, I used the warmer and more velvet Shanling M6 Ultra which also is a very nice listening experience. I don’t think it matters. The tuning of the FD15 is such that there’s no real peaks to be exaggerated by a source. For instance, it has no real spiky treble peaks where a colder source would push them to sharpness. Vice-versa, the FD15 isn’t veiled or “bassy” either and so a warmer source isn’t going to exaggerate the warmth. The world of sources is your oyster with the FD15. Pick one and have fun.

What do you need? ​

I’ll be honest with you, the Fiio FD15 is one of those sets which honestly works and sounds good on… anything. It just does. It’s not neutral/bright, or warm/neutral, it’s neutral. Also, it is very sensitive so using a less powerful source really isn’t an issue. Like I said, pick a source and have fun. Of course, a bit more power does tighten things up a bit, but I don’t think that more power is “needed”. Pick one and have fun.

Sound Impressions ​

Note: before I get into the sound portion of this review I should first state that I most certainly burned this set in. Folks, the FD15 has a 13.8 mm driver and I feel that it does help to burn-in this larger DD. I had them on the burn-in rig for right around two full days, maybe two and a half. Also, I listen primarily to flac or better files stored on my devices. Mostly I use UAPP (USB Audio Player Pro) and for some dongle dacs I use Hiby Music Player as well.

How does it sound? ​

The Fiio FD15 is what I would consider an almost dead neutral iem. Timbre is about as natural as it gets. Very clean-organic sounding. I hear a very good balance across the mix in what I would refer to as a U-shaped sound signature. Almost mid-centric yet with a subtle low-end elevation as well as a boost in the upper regions. Still, it has a wonderful balance dynamically. Just a sweet sounding iem folks. As the predecessor to the Fiio FD5 you’d think the bass would play a much larger part in the tuning, but I find the bass (which is very good) to be more of a supporting role. Instead, I feel the main focus rests in the mids to upper mids. I keep thinking of words to describe this set and I keep coming back to… Sweet. How do I describe something which is simply pleasant? Across the board too. Nothing about this set is shrill, peaky, veiled, artificial, sibilant. I’m telling you all right now it is a timbre-first, neutral-musicality focused iem with nothing fatiguing. Let’s go with five words, top of the head to describe the FD15. Again, sweet, balanced, tuneful, stainless (both in build and in sound), natural. Those are my first five folks, and I stand by them. A wonderful sounding set which still holds good energy, decent dynamism, and even nice extension both ways, yet it never seeks to offend. Nothing about this set goes too far. It has linear dynamics, and it’s great.

Mellifluent ​

I’ve had a wonderful time getting to know the FD15 much in the same exact way that I enjoy the Kiwi Ears Orchestra Lite. In fact, the FD15 could be considered the dynamic driver version of the Orchestra Lite, to my ears anyways. The reason I know this is because the Orchestra Lite is one of my absolute most favorite iems at any price point. Subtle differences but very close. Timbre like the Aful MagicOne, or like the Aful Explorer 5 yet with slightly less bass. Just a musical sound that oozes mellifluousness. Similar to the Dunu Kima/Kima 2, yet more refined across the board. It’s in the same vein as those sets though. The FD15 won’t highlight every last micro-detail or tiny little subtlety within your music. It isn’t analytical at all. Yet it is ridiculously clean sounding. Great clarity, black background, smoother than it is crisp, with a rhythmic style of sound. It’s a set that flows, like waves in the sea. Vocals for days! It trades hard right angles for curved surfaces, nothing jagged, nothing abrasive, nothing edgy. This set is glass-lined through-and-through. It’s honeyed and dulcet with a euphonic style. Truly a special single DD at its price. That’s if you enjoy this type of sound.

Bass Region ​

The low-end of the Fiio FD15 is a high-quality bass. You won’t see any bassheads seeking out the FD15 either. This is not a set for bass-bois. So no, you won’t want to pursue the FD15 if you are into heavy bass. Those who will enjoy this bass are those who enjoy “good” Bass. That said, I also don’t feel the FD15 lacks at all. It’s a nice and marginally meaty bass. This is also a high quality low-end which really does a good job at defining the lower portions of the mix. I hear nice speed as transients move along swiftly yet retain enough harmonic lag to come across slightly atmospheric. This is a low end which can take on slightly speedier tracks down low as well. I wouldn’t put them in the same conversation as planar sets or some BA sets, but the speed is great. Couple that with the fact that the bass sounds very naturally authentic and what you have is a winner in my opinion. The low-end never overstays its welcome and doesn’t infringe on other areas of the mix to any detrimental degree. I’d say its slightly sub-bass focused but that is easily debatable. Very well textured too and does so with decent note density. I hear a solid note surface, nothing pillowy, nothing fuzzy. Basically, the low-end is clean.

Sub-bass ​

I haven’t completely agreed with myself that the FD15 is “sub-bass focused”. Different tracks tell me different truths about the low-end. However, one constant is that the sub-bass is very clean. Perhaps it could use a hint more guttural emphasis down low, but I haven’t heard any track where I feel the FD15 lacks. In fact, extension into the lowest of the lows is deep. Not lacking. No sir, this is a nicely robust sub-bass, yet it isn’t emphasized to the point that it steals focus. It’s balanced so well with the rest of the mix. No offense at all. That is an important detail about the sound. However, this is a sub-bass which will show up in tracks that present a lot of sub-level info. For instance, “Tell Me What’s on Your Mind” by The Decemberists is a track which will rattle and reverb in the back of most eyelids. The FD15 replays this track’s bassline with solid haptic feedback and vibratory goodness. Enough to “feel” the bassline as well as come across deep pitched and dense. Just not overtly lifted like so many sets.

Good supporting actor?​

It’s natural to my ears. That’s what the sub-bass is on the FD15. It shows up when it’s needed and doesn’t needlessly affect other areas of the mix when it isn’t needed. Again, there’s a very nice balance here. However, the sub-bass is very clean. It’s clean at attack, quicker in decay, no real dragged-out resonant harmonics and extra fat to the sound. Notes are well defined, textured, and compact with a solid note structure. Fiio also did a nice job of giving the FD15 a quality bass down low which isn’t at all one-noted, flabby, sloppy, muddy, or too bulbous. Trim but rigid, shows up when it’s called upon and a good supporting actor.

Mid-Bass ​

I would venture to say that the mid-bass somewhat plays second fiddle to the sub-bass but it’s really not cut-n-dry. Once again, the mid-bass is the type which can come across full enough and meaty enough when called upon. I hear a slightly softened attack yet with a quick decay. Certainly not pillowy either. More like solid note density wrapped in a thin layer of cotton. Okay that was a terrible example, but I think you get it. It’s a very pristine bass which hangs its hat on quality, texture, resolution, speed and good timbre with a nice slam to it. For instance, songs like “2040” by Lil Durk carry a fairly heavy bass drop in which I found the FD15 is able to show up in a satisfying way. Really a clean drop, no fuzz at the edges, precise, and doesn’t tend to mask other frequencies. The mid-bass is also pretty nice for bass guitar, kick drums too, yet it doesn’t have the most authoritative hollow boom that I’ve ever heard. “Billie Jean” by Weezer is a track I always use for testing because the kick drums hit right away, no waiting around, and they are one after the other. What I like about the FD15 is that the notes are very concise. I hear a sticky leading edge on attack and a moderately heavy boom. The kick drums are quickly trailed by a sharp and snappy snare drum. It’s nice for sure, though some folks may want a heavier and more weighted sound that the FD15 wasn’t really tuned to provide in full.

Mid-bass cont… ​

That all said, the good thing about this bass region is the fact that it’s got very nice note definition, and it can take on some fairly speedy bass tracks, timbre is great, and the whole presentation is clean. Again, nothing muddy at all and nothing sloppy. What I hear is clean precision with enough weight and density to satisfy most genres just fine. Finally, I don’t hear the bass encroaching on the midrange very much. The mid-bass has great resolution, tight notes, not overwhelming, and it is very nice to hear at this price.

Downsides to the Bass Region ​

I think the biggest issue with this bass would be a subjective matter for those who simply enjoy more amplitude from this part of the frequency. Those who want a more earth rumbling weight and a darker and heavier drone will likely want to keep looking. Like I said, definitely not for true bass heads. However, this bass is for those who enjoy very good and quality bass. I’m sure some people may want a bit more excitement and fun out of their low-end, and I totally understand that. It just means that the FD15 probably isn’t for you. Bass is so very important, well, every area is important, but the bass is the foundation and getting it right will dictate a lot about the rest of the mix. The FD15 is wonderfully balanced, never over the top, timbre is great, note structure is great, note definition is solid. There’s a hint of softness on attack on some tracks but overall density is good and transient decay/sustain is on the faster side of the aisle.

Midrange​

If you ask me, the Fiio FD15 is a mid-forward iem. Certainly not recessed to my ears. The FD15’s midrange has a very musically engaging sound in which vocalists are put on a pedestal. I hear a very smooth sound that doesn’t exclude some crispness when needed. Note weight is lean-lush, semi-rich, or any other mix of words describing notes which aren’t too heavy, yet not too thin. The mids are energetic yet without the glare, lively yet without the sharpness like so many midrange boosted sets. It’s really a sweet-sounding midrange. On top of that, timbre is very natural. The engagement factor is high as the FD15 has a certain elegance in its cadence, an unforced symphonic quality which is always fluid, graceful, and rhythmic. Can you tell that I enjoy the FD15? Just a little. Very much like the Kiwi Ears Orchestra Lite in its effortless ability to convey my music. Again, it’s smooth across the board while also coming across with a very precise and accurate rendering of midrange notes. Always moist, supple, and never dry or clinical sounding.

Charming ​

Now, it’s true that you won’t get the most pinpoint and detailed listen from the FD15 as its fluid and melodic nature leans heavily towards the musicality end of the spectrum. Yet you also don’t really miss out on details either as transients are still rather quick, notes are still well defined, clarity is still… crystal clear. I’d say the FD15 has a clean way of expressing macro-details and about average in the micro. The FD15 simply doesn’t have those hard etched fine lines drawing distinction between each note in a “detail-beast” fashion. It isn’t dry, papery, or artificially boosted either. In my opinion a natural type of sound… probably isn’t the most “detailed” way to listen to music. I think authenticity of timbre is more musical than analytical anyways. Real life doesn’t provide high-resolution, zeroed-in, thin, and etched-out notes. Also, I would hate for this set to lose any of its engaging qualities just for a few easier to discern details. No way! All in all, the FD15’s midrange is charming to the core. From the low mids to the upper mids you won’t get shout, glare, sibilance (to any great degree), or any metallic tinge at the crest of notes either. Really a high-quality midrange which begs me to listen to vocalist heavy tracks. Having said all of that, it goes without saying that this type of replay obviously won’t be everyone’s favorite. You do have to enjoy a more mid-forward style earphone. This isn’t a V-shaped type of sound. It isn’t just exciting at the edges.

Lower-Midrange​

The low-mids definitely come across neutral in tonal color. This isn’t a situation where the bass is feathered-into the mids adding copious amounts of warmth and weight. However, I don’t consider the low-mids to sound lean at all. They have good presence and good clarity which makes up for not having the fullness of a warmer note. My opinion of course. The low mids have a very vivid style, up front, centered, and not so far forward that they sound unnatural or boxy. Actually, male vocals sound very good. Take The Red Clay Strays in the track, “I’m Still Fine”. The lead’s voice has an edginess to it, almost raspy, and it’s so easy for some sets to portray his vocals unauthentic. Especially when he uses more breath and begins to belt out. I love the smoothness and chiseled-out way that the FD15 centers his vocals as the focal point and not in an aggressive way. Or Chris Stapleton in “Sometimes I Cry”. Another voice that sounds wonderful with the FD15 in my ears. His is an even more raspy, edgy, and even sharper voice. I enjoy when Chris reaches those high notes that the FD15 has a way of sanding them down. Never too abrasive. While the rest of the time his voice is full, clean, not grainy, and sounds effortless with the FD15.

Upper-Midrange ​

The upper portions of the midrange are so well laid out. I really mean that. Females eclipse male singers with this set by a slight margin for me. I just feel the FD15 is tuned in such a way that females can come across completely dulcet and alluring due to the great energy in the upper-mids which never seems to offend. Something not many sets are able to accomplish. Instruments are very natural to the ear too. Percussion has some snap and some edge to them without sounding coarse. Strings sound great with the smooth yet clean sound in this region. Just enough crispness, yet forward too. It’s a nice mix. At any rate, instruments generally sound great. Of course, that can change from track to track, recording to recording. Now, the upper-mids are a hair closer to the listener, but not by much. I still hear a more neutral sound, slightly brighter, a little more vibrant, even shimmery while never coming across dry. Female notes tend to have some body to them, some sugared richness. Not rich in the sense that they’re weighted, warm or thick. More like milky, clean note outlines, organic, moist. I hate the word “moist” but it serves its purpose here. Females sound great. Like Adele in “Hello”. She sounds fully emotional, wholly engaging, and very well highlighted against the rest of the mix. Almost haunting. I get this from many females, but this was the song playing in my ears at the moment. The point is the upper-mids seem made to replay female vocalists in a very sonorous, almost euphonious and liquid way.

Downsides to the Midrange ​

I would first probably say that those folks who only dig warm, weighted, and an even fuller sounding midrange probably won’t like the neutral canvas of the FD15. Detail-heads will not be impressed either. The FD15 is not going to impress those who love to pick apart every last detail in their music. Not that the FD15 lacks in detail retrieval, but it won’t blow your mind with its resolving abilities. Folks, it takes all kinds in this hobby and no two are exactly alike. I could sit here for hours exploring different types of listeners and how the FD15 may or may not fall short for them. To be honest, I have a very hard time saying anything negative at all about the midrange on this set. It is awesome to me. I’ve had so many listening sessions, late at night, in bed, eyes closed and just swimming in the way the FD15 captures certain inflections. The way it smoothly, yet so vividly replays certain instruments. Also, I realize I went pretty hard for the FD15 in this section. For all intents and purposes, I’d do it again and again. Really a nice sounding midrange. One of the better in the price point in my humble opinion. That all said, is the midrange enough?

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Treble Region ​

The highs on the FD15 generally runs smooth. Have you noticed a common theme? Once again this is another region where I don’t hear anything offensive to the ear. As though Fiio took this tuning right to the brink of my comfort and capped the brightness there. The treble region actually has solid energy as it isn’t a rolled off treble. Not by any stretch. However, it isn’t an ultra-brilliant/bright type of treble either. Not a treble head’s paradise. Like the rest of the mix, the timbre is also very nice up top and also like the rest of the mix the treble isn’t the most detailed or analytical. You don’t have any of that forced resolution by boosting the treble to illuminate the minutiae. There’s nothing even remotely artificial sounding. Very nice timbre, very natural to the ear. A real “even keel” type of treble. In fact, between 2k-8k there is a substantial dip, almost a linear dip too until some energy pops back into focus after the presence region. Roughly anyways. What this does is bring upon a very easy to handle treble region that doesn’t sound harsh, sibilant, or splashy.

Pretty darn nice​

Despite that, the treble has plenty of sparkle, plenty of controlled brightness and very nice extension into the upper treble. I don’t miss any energy in this region and to me the treble fits the overall tuning very nicely. I’d say there’s enough actual emphasis to lift the overall tonal color of the spectrum while not washing out treble notes in a mishmash of treble tizz and splash either. Again, not a treble head’s dream, but fantastic for those who love a treble which promotes an overall musical sound. However, with that musical sound you also have enough emphasis up top to bring on some presence of air and openness to the sound. Certainly not rolled-off, dark, or congested sounding. There’s an effervescent and open “feel” to the sound. To an extent anyways. This helps with stuff like instrument separation, layering, and helps to simply hear each note somewhat distinctly. I’m not saying it’s some enormously vast breadth of open space, but for a smoother sound which is mostly non-glaring, non-offensive, and non-analytical, it’s pretty darn nice.

Not the best, but good​

I just said that detail retrieval up top is not going to amaze the listener, but in the exact same breath I also don’t feel that you will necessarily miss out on very much. Once again, we have a smoother presentation, not as much crunch, or treble bite as some other sets. There’s some lack in that regard. If you consider that “lack”. Basically, there are many other sets which perform much better in the treble if “better” (to you) means analytically refined, transparent, crisp, ultra well defined and some sets have more of a haptic “feel” to each treble note. The FD15 is a milky ride along easy moving wave. Obviously, there are plenty of hybrid sets, planar sets, or multi-driver sets which have greater capabilities in this region to separate instruments, define notes, form contrasts, stuff like that. What the FD15 does so well in this region, and every region, is that they come across natural, timbre-correct, coherent, and extremely musical without any damning sharpness. So no, detail retrieval isn’t going to be top-class and those who yearn for a more precise note body and crispness won’t exactly find that here. Still, you have very good extension, cymbals don’t sound splashy, have solid note body, and they are distinct. Also, details are still pretty nice simply due to the cleanliness of the sound as a whole. Again, you aren’t missing much.

Downsides to the Treble Region ​

This is very much a preferential downside, but I’d say that anyone who really desires an edgy, highly precise and brilliant treble region will likely not be very impressed. Again, the FD15 presents the treble in a smooth manner, semi-bright yet non-offensive. So many folks that I know love just a sprinkling of offense. They like that hard, crisp, defined, and biting note edge. The type of treble that you feel as much as hear. Those types love a treble which comes across bodied, but also with solid density and treble punch. The FD15 isn’t quite that. It is very clean, timbre is great, fits the overall tuning well, and the extension is very nice. Yet it doesn’t have that type of demeanor where every last micro-dynamic and subtle detail sounds perfectly evident. Smooth and easy doesn’t really give you that. Still great for what it is and for the style of the tuning but of course it won’t be for everyone.

Technicalities ​

Soundstage ​

This is another bright spot for the FD15 as the soundstage actually comes across pretty vast. The FD5 was the exact same way. Something about Fiio’s acoustic cavity really helps the sound to come across in a larger sense. You also have good extension both ways and a fairly dynamic sound as a whole. Whatever the contributing factors are, the FD15 certainly has an above average stage and a more holographic presentation too. I’d say width is above average, height is too, and depth is pretty nice as well. In fact, I find that the depth is great for layering of instruments which helps with imaging as well, but I’ll get into that in a minute. As far as the stage is concerned, it is closer to the listener. So, while the stage is very full, with good width, height, and depth, it’s also more up front. You don’t get that stadium feel. We see so many iems lately with a more forward and closer, more intimate setting. Still, in my book the soundstage is a bright spot for the FD15.

Separation / Imaging ​

Instrument separation throughout is actually quite good, even with a smoother take on my music. The FD15 is very clean folks. That cleanliness, black background, and transparent type of replay helps even a smoother set to sound decently well separated. I honestly don’t have an issue hearing instruments in a relatively well contoured manner. There is some space between. Of course, I have to mention that the FD15 won’t fare as well against more complicated and congested music. Ultra bass-heavy songs may pose a problem as well (who’s listening for separation in Ultra bass heavy songs?), and obviously poorly recorded jams won’t help the FD15. So, while it isn’t class leading, the FD15 performs well for what it is (single DD) and for how it was tuned. Imaging follows the exact same line of thinking and really follows suit with its instrument separating ability. Actually, scratch that, Imaging is great. The FD15 is able to create some layers to my music. Some front to back depth of field which helps to hear those drums further back, kick drum dead center, the acoustic guitar at the front right, the cymbals spread wide for example. Of course, not every track follows that spread. That was just an example. Anyhow, if you have a nicely recorded track which isn’t too chaotic then the FD15 will perform very well and images the stage nicely.

Detail Retrieval ​

Like I’ve said this entire review, the detail retrieval on the FD15 from Fiio is certainly, at the least… average. That’s the worst it’ll be. Which is actually quite good. No, the FD15 won’t create perfectly contoured and intricate fine line and concrete-discreet note outlines as it isn’t a dry, ultra transient tight and clinical type sound. It isn’t forced bright or boosted to try to illuminate all of the little data points and intricate sound info which some sets are unkindly tuned with (we all know the downsides there). Also, the FD15 is smooth, it glows rather than illuminates, it’s moist in body, very clean but not edgy. Again, it’s all rounded corners and wavy lines rather than right angles and straight lines. Basically, the FD15 won’t be considered the best technical set in its price point, but it may surprise some folks even with its penchant for musicality. About average in some tracks and above average in others.

Full Review Here

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Comparison​

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Fiio FD5 ($300) ​

I felt this comparison was necessary, albeit, maybe not very helpful, is with the FD15 and its predecessor, the Fiio FD5. The FD5 is a legend set folks. I mean it was and still is a banger of an iem. Truly a. Special set which still holds up. Maybe not at $300, but it holds up for sure (by the way, the FD5 can be found for cheaper nowadays). Now, the FD5 is another single DD and happens to be the predecessor of the set I’m reviewing today. In fact, Fiio states as much in eir promotional material. The FD15 is basically “part 2” of the series. So, the FD5 has one rather large 12mm Beryllium Coated DLC Dynamic Driver and has a semi-open build to it. The FD5 also has a ton of acoustic physical tech going on inside of its cavities, just like the FD15. It too has tuning nozzles and is also accessorized quite well. Friends, I’ve owned this set since its beginning, and I have enjoyed it the whole way through. It has been a constant in my collection and one that I still reach for every now and again. Always reminded why it’s so special. That said, there are a number of differences between these two sets, even with all of their similarities. I’ll try to help those words makes sense. Lol.

Differences / Similarities ​

Both sets have darn near the exact same housing size, shape, and somewhat similar designs. Now, the newer FD15 is a hair heavier at 12 grams to the FD15’s 11 grams. So basically, the same. Both are fairly heavy relative to their size. Yet also, they are both made out of stainless steel and both superbly sharp looking. I do consider the FD5 the better looking iem but I truly enjoy both of them. I just like the FD5’s brushed metal faceplate and semi open design. It looks beyond dope. Now, the FD15 fits me much better, and I chock that up to the fact that Fiio changed the insertion angle of the nozzle. That additional 7.6-degrees really helps for me. Of course, the FD5 has a semi-open faceplate to the closed-back FD15. The FD15 has a substantially larger driver with a 13.8mm DD compared to the FD5’s 12mm DD. The FD5 uses a Beryllium Coated DLC to the FD15’s Magnalium (magnesium/aluminum) and DLC DD. Also, while the FD15 has a great unboxing and probably the better modular cable, I find the FD5 to have an even better accessory stack. It’s got a better unboxing and is more premium by a slight margin. Most certainly a better carrying case. Actually, the FD15 doesn’t even have a case, it has a drawer, with Lego pegs on it. Weird I know. Honestly, the FD5 just feels and looks a hair more premium, more stately, higher end. But it is only by the tiniest of margins folks. Remember, the FD5 came in with an MSRP of +$300 whereas the FD15 costs half of that. Which is wild. So, I guess that explains the presentation difference.

Sound Differences ​

I’d say the FD5 is quite a bit more V-shaped sounding to the U-shaped and mid-forward sound of the FD15. They are actually two completely different tunings. Good compliments to each other. The bass is thicker, fuller, and more authoritative on the FD5. However, the bass on the FD15 is cleaner, better defined, more agile, better layered, less one-noted. However, the FD5 is simply boosted more in this region, yet very clean in its own right and much more haptic and guttural. The midrange of the FD15 is more musically gifted, melodic, even slightly cleaner sounding. Now the FD5 actually sounds more detailed in this range yet with a greater emphasis in the pinna rise which can sound shouty at times. The FD15 doesn’t do that, it’s balanced, forward, easy, and probably the better midrange (for me at least). Next, the treble on the FD5 is brighter, better extended, more intricately defined, better detail retrieval, more bite, and simply more brilliant. While the FD15 is less offensive, smoother across the range and still very clean. Technically, the FD5 “probably” has the upper hand, as it’s just more detailed, better instrument separation. However, I find imaging abilities if both sets are on part with each other, especially in less intense tracks. The soundstage of the FD5 is more open, airier, and probably a hint grander in size. Yet I do find the FD15 to be every bit as deep and just as well layered. So, the FD5 is more energetic as a whole, while the FD15 is better balanced. Two very different styles of listening.

Final thoughts on this comparison ​

I would certainly call these brothers a preference battle. If you like an energetic V-shaped sound then the FD5 would likely suit you, but if you enjoy an even sounding, much more tuneful and balanced sound with a forward vocal-centric take on your music then maybe the FD15 is a bit better for you. In truth, these are two sets that I really enjoy, for different reasons of course. Both are fantastic sets which shows off Fiio’s abilities to engineer and design. I personally enjoy the newer FD15 a bit more and feel that it is better suited to my taste at the moment, but I will always like the FD5 quite a lot.

**I could not find a comparison graph between the FD15 and the FD5, so I added the next best thing. That’s a graph of only the FD5 below.**

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Is it worth the asking price? ​

I will answer this question quickly and very decisively… absolutely the Fiio FD15 is worth the price of $149! Of course it is! I would pay that price again and again. Of course, this answers this question for me and my personal taste and doesn’t account for everyone. To one it’s well worth the $149, and to another the FD15 may not be. That’s the nature of this subjective hobby. However, for this guy I truly enjoy what the FD15 brings to the table and how it portrays my music. Again, very similar in almost all ways to the Kiwi Ears Orchestra Lite. Just a fine-tuned and very impressive tuning that never causes fatigue. If you enjoy just putting a set in your ears, closing your eyes and getting lost in your music then I would certainly advise you to check out the FD15. I will say that there are some genres better suited for other sets and there’s different sound signatures that I enjoy “at times” a bit more. I actually enjoy all sound signatures folks and so some days I might want something warmer or heavier in the low-end. Maybe even brighter, more detailed and analytical too. I bounce around a lot. Still, for $149 I feel this is a steal at that price.

The Why… ​

Because this set is built like an absolute tank. Made entirely out of beautiful stainless steel and polished to a mirror finish. Just beautiful! Wavy lines capture the faceplates looking more like jewelry than anything else. Also, it’s cylindrical body fits my ears very well, very comfortable for me. Next, the unboxing is fantastic for a $149 set. Other than the weird case (you may love it, so I’m sorry), I love the modular Furukawa SPC modular cable as it looks amazing with the FD15 attached, a ton of tips and a premium presentation. Good job all-around for Fiio on this one. With all that said it’ll always come down to the tuning and sound. As always. Folks, I think this is one of the most pleasant sounding iems to come out in a while. Musical through and through. Not the kind of musical that’s rich, warm, and engaging, but engaging in its perfect timbre, symphonic and mellifluent lean, and its ability to never seem to cause undue sharpness. Just a wonderfully clean and balanced sound from the sub-bass to the upper treble. Bass is quick, textured, tight, and well defined. The midrange is an instant classic with wonderful vocals across the board and very pristine. Wonderfully melodic. The treble is non-fatiguing, still brilliant and open sounding but not overtly so. The soundstage is wide, tall and deep with great imaging and layering capabilities. I think this set is easily worth the cost of ownership and I am happy to own them.

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Ratings (0-10)​

*Note: all ratings are based upon my subjective judgment. These ratings are garnered against either similarly priced sets or with similar driver implementations or styles with the unique parameters of my choosing. In the case of the Fiio FD15 ratings below, that would be $100-$199 single dynamic driver earphones. Please remember that “ratings” don’t tell the whole story. This leaves out nuance and a number of other qualities which make an iem what it is. A “5-6” is roughly average and please take into consideration the “lot” of iems these ratings are gathered against. $100-$200 is not a very large sized scope of iems. So, It should be fairly easy to see a rating above a “9.0”. My ratings are never the same and each set of ratings tells a different story. Each time you read one of my ratings will be unique to that review. Basically, I create a Rating that makes sense to me.

Aesthetic ​

–Build Quality: 9.9 Wonderfully built.

–Look: 9.8 Love the look of this set.

–Fit/Comfort: 9.0 Fit and comfort is very good for me.

–Accessories: 9.6 Nice unboxing, far above average.

–Overall: 9.6

Sound Rating ​

–Timbre: 9.9 Completely natural, great timbre!

–Bass: 9.3 Speedy, well defined, textured.

–Midrange: 9.8 100% melodic, vocals are top notch.

–Treble: 8.9 Well extended, non-offensive, clean.

–Technicalities: 9.1 Mostly great for what it is.

–Musicality: 9.8 Musicality is its life blood.

–Overall: 9.5

Ratings Summary:​

Okay, before you go any further, I need to preface a couple things because so many of you message me about these “things”. First, please read the note under the header for this section. I outline “what” I’m comparing the FD15 against, as well as “what price range” I’m comparing the FD15 against. In the above note I said that I’m comparing this set against all “SINGLE DD” iems between $100 and $199. I don’t do across the board ratings, mostly because those are too broad, even less nuanced. I do ratings according to the consumer. I’m not saying mine are perfect, but they make more sense to me and hopefully to prospective buyers. Each rating on every review is different. These are on the spot comparisons with every earphone I have in my arsenal, and I rate them on the fly. It takes some time to do. At least a two-hour rating/comparing period for every review depending on how many I actually have on hand. Very few times have I rated something against a set that I didn’t have in my hands, physically. I rate using songs which pertain to each rating. Maybe one day I’ll begin sharing those songs. Sorry for this explanation by the way but I feel I needed to speak on that.

READ​

Anyways, please don’t message me saying that I gave the Fiio FD15 a “9.5” against every set on planet earth! READ. I gave it a “9.5” overall sound rating against single DD iems in the price range of $100 to $199. You do the math. Think of the single DD sets in that range. Sorry if this comes across coarse. I really don’t want to. However, I get at least 10-15 (sometimes more, sometimes less) messages about these ratings and I have to re explain myself. Maybe I need to do away with ratings altogether. You guys all know how I feel about them.

Explain Yourself! ​

The one rating which jumps out at me and is usually the subject of most messages and complaints is the “Bass” rating. I gave the Fiio FD15 a “9.3”. I think that’s fair. It’s tight, very clean, of very high quality, and nicely textured, nicely layered. In truth, I wanted to give it a higher rating but held back only because it could use some a few more db’s. That’s it. It is a wonderful bass. Now, bassheads wouldn’t give this set a “5.0”, mainly because they like… heavy bass. This isn’t that. Next, how in the world could I give the FD15 a supremely lofty rating of a “9.8” in the midrange, it isn’t even the most detailed? So, this is where subjective preference comes into play. I think it’s easily the best midrange out of all single DD’s between $199 and $200. That’s it. It’s the best and so it gets the highest score. Same goes for the “9.9” I gave the FD15 for timbre. Because against single DD’s within the specified range, it’s the best. Again, for me. You may feel differently, and I wouldn’t ever dream of arguing with you about it. Because you are you and I am me. The rest of the ratings I don’t think need very much explaining. One more thing, now that you’ve read my little rant, please pay these ratings no mind. Don’t let them hold water. Grains of salt folks. Unless you really trust every word that I write and know what I enjoy, I’d just keep scrolling.

Final thoughts on the Fiio FD15 before I conclude ​

What a set. What a fine set. Is it perfect? Absolutely not. No way is it perfect, it has many little issues. It isn’t the most fun sounding, sub-bass isn’t the deepest, doesn’t slam with the most impact. The mids aren’t the most detailed, separated, and aren’t the most technically inclined as a whole. Of course, the treble region isn’t the most brilliant, crisp, biting or most contoured. There’s a lot of subjective gripes that some could have. The beauty of this set is that it isn’t supposed to be all of those things. The FD15 is supposed to be exactly what it is, mid-forward, vocally gifted, very musical, and easy in the ears. I that vein, it’s a wonder of a set. Truly a special single DD. Without question it will not be everyone’s favorite, and I really hope my words have helped you to decide if it works for you, or not. I think Fiio absolutely nailed this set and did a very fine job crafting a gorgeous iem that stands out aesthetically within its price point and is built to last. I am more than happy to own it and happy to be able to listen and get lost in its sound. With that said, I most certainly recommend the Fiio FD15, if, you enjoy that mid-centric, mid-focused sound, musicality first, with a great balance across the mix. If that aligns with you than it’s an easy REC.

Conclusion ​

To conclude my full written review and feature of the Fiio FD15, I want to thank each and every one of you for taking the time out of your day to click the link and spend some time here. I highly doubt there are many of you still reading this, but for those who are, I cannot thank you enough. Writing these reviews is an absolute joy for me, and I do so first because it is a crucial creative release for me. I love it. However, a close second is that I do this for you. Those are the reasons. Hearing that any word I wrote made your listening experience better will always be like joy washing over me. That’s the truth. On top of that, mobileaudiophile.com thanks you as well. It is because of you that we are able to continue to write reviews and publish to this awesome website. So, thank you very much.

Other perspectives ​

Now that I’ve thanked you for checking out my review, I also hope that you’d check some other reviewers’ thoughts about the FD15 out. There are so many good reviewers out there folks. Just solid people who really do a good job breaking down these products. Many of them are my friends, and many of them have fantastic takes personal to them. I hope you’ll listen to, watch, or read other reviews and perspectives so that you can gain an even better understanding of what you are getting with the Fiio FD15. Folks, we are all very much different. The guy sitting right next to me may have a completely different opinion than I do. I think you know that I really like the FD15, but the next guy may not. He may hate this set, who knows. Or maybe he loves it too. The point is, it’s just more info to help you make an informed purchasing decision. I am not the last word on audio, and I do have my own subjective likes and dislikes, so does the next guy. So please click on some more links. Okay, with that all said I think I’ve covered it all. Please take good care, each and every one of you. Stay as safe as possible and always… God Bless!

The FiiO FD15 is a single dynamic driver earphone, the successor of the much acclaimed FiiO FD5. This new model introduces many techonoligal novelties over the previous one but surprisingly it is much more affordable as it sells for $159 instead of $299. And this reduced cost comes without skipping on accessories except the luxurious carrying case that is no longer included.



Technical stuff

With the FD15, FiiO introduces a high-end driver design with a 13.8mm large, magnalium diaphragm DLC driver. The Magnalium diaphragm mixes magnesium and aluminum for high hardness and low distortion, while the DLC gasket provides rigidity and flexibility for higher sound quality.
The FD15 also features a W-shaped driver suspension that increases the effective vibration area by 30% and an 8.6mm voice coil that increases driver power by 78%. The external 1.5T magnet design ensures consistent performance, and Tesla Valve's patented Bass Enhancement technology ensures deep, high-quality bass. A frontal acoustic prism with adaptive phase adjustment, enhances the high frequency diffusion.

For more information you can visit FiiO's official website.

https://www.fiio.com/fd15



Non Audio stuff

The design and appearance of the FiiO FD15 are similar to that of the FD5 but there are many hidden innovations employed for improved ergonomics that are not visible at first sight.

The angle between the sound nozzle and the wearing surface along the Y-axis is precisely adjusted, raising it by 6.7⁰ while maintaining the length of the nozzle. The result is that the earphones fit much better into the ear canal, significantly enhancing wearing comfort and stability.

The typical rigid right-angled cylindrical MMCX shape has been transformed into a more ergonomic curved shape to better accommodate a wider range of ear sizes. This design eliminates the discomfort caused by the earphone pressing against the back of the ear.

FiiO has also narrowed the contact area between the front of the IEM and the ear to ensure a better fit by reducing the movement caused by gaps and minimizing friction.

All these small but meaningful innovations, together with the compact and cylindrical shape of the FD15, translate into a comfortable and stress free wearing experience despite their weight that is a whole 12g per piece. The FiiO FD15 is more comfortable than the FD5 and offers a stable fit with very good passive noise attenuation.



The FD15 is exceptionally well made and finished, it is shiny and beautiful with a minimalistic and luxurious appearance. The FD15 reminds more of a precious jewel than your typical earphones.

The ear shells of the FD15 are made from 316L medical-grade stainless steel by using a special process of powder metallurgy and then they are hand polished and electroplated. The FiiO FD15 is available in obsidian black and silver finishes.



Cable

The FiiO FD15 comes with a high quality, detachable cable with MMCX connectors. The wires are made from a combination of Furukawa monocrystalline copper and Furukawa monocrystalline silver-plated copper in a braided design. It consists of four large strands, each made up of 100 copper wires and 20 silver-plated wires for an overall total of 480 wires with a cross-sectional area of 22 AWG.

The cable also features a straight twist-lock swappable audio plug, 3.5mm and 4.4mm options are included in the bundle. This is a high quality cable that is durable, it doesn't get tangled and has minimal microphonic noise, however it is heavier and thicker than the ideal for portable use.



Accessories

Please refer to the following picture for the included accessories. This is an all-inclusive bundle, the only thing missing from the original FD5 package is the premium carrying case that is now substituted with a plain plastic one.



Sensitivity and associated gear

The FiiO FD15 has a rating of 32Ω with 112dB/mW of sensitivity thus it is unfussy when it comes to driving. Just use high quality portable sources, like the FiiO KA17 and the FiiO M11S because the FiiO FD15 scales pretty well and entry level gear will not do it justice.

Audio stuff / Black nozzle

For the FD15 FiiO has decided to depart from the V-shaped tuning of the FD5 for a more neutral approach. The FD15 has a mildly neutral and balanced tuning with more prominence in the mid-range rather than the extremities of the frequency spectrum.

Sub-bass is extended enough but not too emphasized so it has the means to reproduce the deepest notes without overpowering the rest of the frequencies. The tuning is accomplished in such a way to offer plenty of rumbling bass but in an even and balanced way. The bass is almost neutral with a smidge of mid-bass prominence that adds some nice warmth and body to the sound while staying tonally accurate. Not reference accurate but still the tonality is good enough for listening to acoustic and classical music without much compromises. The bass is precise, resolving and clean enough to sound well defined and layered with plenty of micro detail. The driver has fast recovery and it does without audible cup reverb. Technicalities are good, the bass is tight and controlled with satisfying dynamic contrast and physical impact in a way that can lead you to believe that this is a much more expensive earphone.

The mid-range is almost perfectly balanced with equal presence from the lower to the upper mids that are just slightly elevated to maintain clarity and definition without leading into any kind of harsh or shouting sound. People sensitive in this particular area are going to love the FD15 because it is a mid-focused earphone without the associated fatigue that is a result of the usually emphasized upper mid-range. The pitch is accurate and correct, the timbre is natural and realistic while the FD15 is expressive and resolving. It can reproduce the whole harmonic spectrum with ease, the sound is saturated and harmoniously intense. The textures are lush and well balanced with good body weight, not dry or lean, and with nicely rounded edges. All in all, the mid-range of the FD15 is a real marvel, it is reproduced in a lifelike and effortless manner, the sound is definitely engaging and it manages to connect the listener with the music.

The treble is smooth and controlled but without lacking that much in extension and transparency. It has good amounts of energy and vividness but it does so without sounding bright or sharp as it gently rolls off to avoid any spikes that could cause harshness. The FD15 might not be the first choice for people who like bright, ultra resolving and analytical sound but it is going to be loved by others who have sensitivity and can't stand brightness. Detail retrieval and resolution are satisfying but not class leading, hybrid earphones can do much better in this regard. What they can't do though is to sound as cohesive and holistic as the FiiO FD15 or reproduce the treble in such an organic and natural way.

The soundstage is quite grand, open and spacious enough, with very satisfying imaging and plenty of air around the performers. The sense of depth is not class leading and positioning accuracy might struggle a little bit when the music gets busy but the FD15 never sounds congested or like a blob.



Audio stuff / Red nozzle

The FiiO FD15 comes with two pairs of swappable sound nozzles that allow the user to customize the sound profile of the earphone. If we consider the black nozzle as the standard, then the red one mildly subdues a part of the upper mid-range and lower treble while leaving unaffected the rest of the frequency range.

The perceived audible effect is that of a slightly enhanced bass, more present mid-range and less prominent treble. The sound differences are rather subtle and the FD15 doesn't lose its general sound profile. It just becomes a little warmer and smoother on treble by sacrificing some energy and sparkle but it doesn't become too dark or veiled. Bass quantity and quality remain exactly the same but you get the illusion that is a bit more prominent because of the slightly reduced treble. All other technicalities and resolution remain completely unaffected, this is an effective way of fine tuning the FD15 without messing up with its general character.



Comparison with the FiiO FD5

The FiiO FD15 might be almost identical looking to the FD5, with some minor cosmetic differences, but it has much improved ergonomics and is more comfortable to wear. Furthermore it costs half the launch price of the FD5 and the only thing missing from the package is the luxurious carrying case. Not a bad deal.

Regarding their sound profile, the FiiO FD15 is more balanced compared to the V-shaped FD5. The bass is not as extended on the FD15 but is more neutrally tuned with less mid-bass prominence so it has better tonal accuracy. The FD5 has more visceral and weighty bass but the FD15 edges it in control and overall technicalities. The midrange of the FD15 is more balanced and present compared to that of the FD5 which sounds a bit recessed as it highlights the upper midrange. The treble is more extended and energetic on the FD5 which is also more resolving and detailed but also brighter and not as smooth or forgiving as the FD15. Honestly speaking, none of them is better than the other, they just have a different kind of tuning that each one will appeal to a certain target group. So I wouldn't consider the FD5 as obsolete but if FiiO is going to continue producing it, then they must level its price with the FD15.



Comparison with the Simgot EA1000

The $219 Simgot EA1000 is a single dynamic driver earphone with an additional passive radiator to add some extra juice to the low-end. This is more lightweight and compact than the FiiO FD15 but not necessarily more comfortable. It comes with a luxurious carrying case but a lower quality cable that has a 3.5mm plug. The EA1000 has three different nozzles that allow more options for fine tuning the sound.

With all three nozzles, the tuning of the EA1000 is more V-shaped with a generous upper mid-range lift and more emphasized treble. The tuning is a mix between that of the FiiO FD5, when it comes to the upper midrange and treble, and the FD15 when it comes to the low-end. The EA1000 is slightly more resolving and technical sounding than the FiiO FD15, with better treble extension but it is also brighter, a little sibilant and has a touch of metallic timbre. The bass sounds more hefty and visceral, weightier and bigger in quantity than the FD15 but it is less fast and not that well controlled or layered.



Conclusion

Objectively speaking, the FiiO FD15 is a much improved version of the FD5 when it comes to ergonomics and wearing comfort while it sells for half the price. When it comes to the overall sound profile, things can become more subjective, some people will prefer the more neutral, balanced and mid focused tuning of the FD15 while others will miss the extra bass heft and the more extended and sparkling treble of the FD5. For what it matters, I belong to the first group of users as I much prefer the FD15 for listening to classical music.

Staying outside the FiiO family, the FD15 is an excellent sounding single dynamic driver earphone with a balanced-neutral tuning, a really special midrange and competitive technicalities. It might not be the most resolving or brilliant set of earphones but it sounds expressive with great timbre consistency and plenty of musicality.

The FiiO FD15 is a testament that less is more and nothing can really beat a well implemented single dynamic driver when it comes to sound cohesiveness and timbre realism. People who value musicality and are sick of the Harman target curve and its hundreds of variants are going to love the FiiO FD15.

The review sample was kindly provided free of charge in exchange for an honest review.

The price of the FiiO FD15 is $149 and you can buy it from here and here. (Non affiliate links)

FIIO FD15
1DD Magnalium Diaphragm + DLC Gasket
$150

Before I even start this review, let me thank FIIO for sending me this IEM for review.
Rest assured, this review is 100% my own personal opinion.

Check it here : https://www.fiio.com/fd15

Unboxing
Build Quality


The Shell is purely made out of glossy stainless steel.
Even though the build quality is really solid and it has gone through PVD coating process, the FD15 is quite susceptible to scratches, mine has some scratches out of the box.

Compared to the FD5, FIIO made small changes to the FD15 such as the curvature of the IEM, that FIIO claims to improve the comfort (more on this later), also the faceplate of the IEM is also different compared to the FD5.
The FD15 now featured more like a solid closed back IEM with tesla valve acoustic designs.

As for the cable included with the FD15,it is an mmcx cable.
The cable is made from Furukawa monocrystalline SPC and silver cable. It's great for a stock cable especially on the $150 price.
Not only that, the included cable is also modular, it comes with 3.5mm and 4.4mm jack.
Bravo FIIO.

Comfort
Now here is my main issue with the IEM, even though FIIO claims that they made some changes to its shell design, I still have the same complaints just like the old FD5.
It causes some pain after wearing the IEM for more than 1.5hours, at least on my ears.

The shell indeed can fit more snuggly compared to FD5, BUT the edges of FD15 shell are touching / resting on my earlobe, and due to the solid stainless steel material used for the FD15, the IEM is not exactly lightweight either, just like its predecessor the FD5.

Sound & Comparison to FD5

Tested using FIIO KB3, Stock Eartips, Stock Cable, Both nozzle.
Music is mostly from Apple Music (J-POP, EDM, Rap, Jazz, Metal)

Tonality in general : “Balanced”

I thought the FD15 would have the same tuning just like its predecessor, but no.
The FD15 now features a balanced tuning that really reminds me of other companies' take on Harman target tuning.
It has enough bass to make the sound fun without muddying up the lower midrange, and somewhat tamed upper midrange with just enough treble sparkle.

Compared to the FD5, the FD5 overall tonality is more fun and engaging to listen due to emphasis on bass and treble, whereas the FD15 is much more all rounder and has more vocal shine without any shout and sibilance.

Bass : FD15 bass quantity is much more tame compared to the FD5, but don’t worry, the presentation is very satisfying, good sub bass rumble and depth, with a bit of mid bass coloration.
It sounds full, punchy but not emphasized.
The bass blends in pretty well with the rest of the frequency.
Though if you’re coming from the FD5, I'm sure you will miss the brute force of FD5 bass, because the FD15 doesn’t have it anymore.

Midrange : FD15 midrange is also much more balanced compared to the FD5.
It has fuller lower midrange, with less upper midrange gain.
The vocals sound very good on this IEM.
Both male and female vocals are rendered beautifully, not too forward, but not exactly laidback either, free from shout and sibilance.
As for instruments, such as violin for example, it sounds a bit controlled and not too forward either due to the tamed upper midrange.

Treble : Treble quantity is also now more tamed and balanced on the FD15.
It blends in pretty well with the bass and midrange.
The treble itself is pretty good, extended, airy with zero harshness on its presentation.

As for the difference in nozzle, I found the red nozzle to be more warm (less upper midrange and treble) compared to the black nozzle. The difference of the nozzle is not night and day difference but it is affecting the overall tone of the IEM.
Myself personally prefer the red nozzle due to its more warmer presentation.

Technicalities
Very good for $150

Stage : large for an IEM.
Just like its predecessor, FD15 also has a very good stage presentation, which is pretty large for an IEM.
Stage layering is clearly present and is symmetrical in width and depth.

Imaging : Very good
It can give you a holographic presentation just for $150, no joke.
Even when plugged to my KB3, not exactly a high end source, the imaging presentation of FD15 is spectacular, definitely an improvement compared to the FD5.

Separation & Positioning : Very good
I can happily use the FD15 for short session gaming because of the very good sound separation and positioning.
The pinpoint capability of the FD15 is very good for its price, on par with its predecessor, or I dare say it's slightly better due to its balanced tuning.

Detail Retrieval : Very good
Resolving capabilities of the FD15 are also very good, definitely punching above its asking price of $150 and is clearly better than the FD5 especially on the treble region.
I dare say the FD15 is as good as the Blessing 3 from Moondrop which is 2 times of the asking price.

Conclusion
Is the FD15 any good?
Can I recommend the FD15?

The answer is Yes, the FD15 offers a very good value for its price, it’s like you’re getting an improved technicalities FD5 with different tuning for half the price, which is a crazy move by FIIO.
Though if you’re coming from the old FD5, you will definitely miss the brute force bass power of the FD5.

But again, I must mention the comfort issues that I have with the FD15.
This one is kinda tricky, you may or may not experience this issue, because everyone's ear shape is different.

Thanks for reaching this far !

Just in case you're Indonesian, you can watch the review of this IEM here

-littlenezt

FiiO new Dynamic Driver is a worthy successor to the FD5​

Introduction​

FiiO has been steadily advancing its IEM lineup, introducing a series of refreshed and upgraded versions of their existing product lines. The FiiO FD15 is the latest entry in this progression specifically in the FD (FiiO Dynamic) range, building upon the success of the popular FD5.



Priced at $150, the FD15 boasts several enhancements and aims to provide a premium audio experience in the highly competitive mid-fi $100 - $200 market.

I would like to thank FiiO for providing the FD15 for the purposes of this review. You can read lots more information about the FD15 on FiiO product page here
In summary, don’t let the price tag fool you, this is an extremely high quality IEM that deliveries on sound quality and is built better and packaged better than it has any right to be.

But let’s get into the details as to what you get with the FD15.

Packaging and Accessories​

The packaging of the FD15 is both fairly unique but typically FiiO in that you a nicely premium packaging and some great accessories with within the box.

So it comes in a nice the box:



Opening up you get a small manual - mainly describing how to switch the nozzle:


Removing the manual you get the FD15 in all its glory:


One slightly unique feature of the packaging is instead of the usual carrying case, FiiO provided a clear plastic box to store the FD15:



I love this idea - it is practical (I typically never use the big leather carrying cases that are often provided) while I am already using this container to store the FD15 many accessories:


It also has lego like design and I would love to see more manufacturers providing similar boxes for IEM storage where they could be stacked onto of each other:


Sadly I can’t imagine the industry agreeing to this standard, but I do think it’s a great alternative to mostly useless carrying cases, hopefully FiiO can use this design with future IEM’s.

Inside this box, FiiO have included lots of accessories type you might normally expect in a flagship offering including:

• Eartips: Five sets of various eartips including balanced, vocal, bass, foams, and HS18.
• Other Accessories: MMCX remover tool, cleaning brush, and a set of alternate modular nozzles.

FiiO even provide a few labels for the front of the box.

Cable​

The cable also feels like quality - much closer to the cables FiiO provides with their flagship IEM’s models like the new FH19. Technically it is Furukawa monocrystalline silver + monocrystalline silver-plated copper cable with MMCX connectors and modular 3.5mm and 4.4mm plugs:



It uses MMCX connectors which again is more typical of higher end IEM’s than 2-pin, and it does have some adjustability options over 2-pin connectors:


The modular cable design is practical, allowing users to switch between single-ended and balanced outputs with ease.

FD15 Shell​

I was immediately struck by the weight and quality of each IEM:

If you are coming from sub $100 IEM’s one thing you will immediately notice is the build quality of the shell of this IEM. This is an IEM shell that is built to last, unlike typical plastic molded IEM shells where I am afraid I might accidentally sit on them and break them.

It is almost like in a thousand years some archeologists will find the FD15 and wonder what weird metalic objects people in the 21st century were sticking in their ears, but it will be one of the few IEM shells to survive that long.



I believe some early review units were highly magnetized but mine were only slightly magentic.

But despite its robust construction, the FD15 are relatively lightweight and comfortable for listening sessions, I used this on many long walks (I have been practising for the ‘Camino’ so out walking 3-4 hours each day) and they provided excellent and stable fit in my ears for many hours each day.

Features​

FiiO have implemented some nice technical features unique to the FD15 specifically, I thought the ‘Tesla Value’ to enhance the bass frequencies seems like an excellent design and one that I definitely appreciated the quality of the bass during my subjective listening sessions.

Another innovation I thought was worthy was an adjustment in the angle of the nozzle (it sounds like a small thing) but FiiO technical description matches my own subjective features of how well this IEM fits in my ear and how stable it is.

The alternative nozzle while not unique to the FD15 is worth highlighting:


The stock nozzle (the alternative Nozzle has a red tip):


There are some other technical features which are interesting, but you can read them over on FiiO product page here

Subjective Sound​

So I briefly switched between the two ‘stock’ and ‘red’ nozzles and quickly settled on the stock ones, but to be honest I didn’t hear that much of a difference between them, but I thought maybe the stock one had slightly more ‘detail’.

So I then started my deeper investigations of the sound of the FD15.

FiiO ‘House sound’ and the FD15​

So having owned a few FiiO IEM (and headphones) in the past few years, the key thing to understand is FiiO are not aiming for a ‘Harman’ signature, they have their own unique tuning which is typically includes some rich sounding mid-bass. FiiO also typically like to tune their IEM to emphasise the key features of each release of their product, for example, with the new FH19 you get some very nice bass, smooth treble and incredible soundstage as those are the technical features they were aiming for.

But with the FD15 I was immediately impressed with the clarity of midrange and bass (probably this ‘Tesla’ value provided this benefit and helped with the nice ‘separation’), so pretty quickly I knew this IEM was not the FiiO “house sound” but had a subtly more balanced midrange than in my previous experience with FiiO IEMs.

In short, I love the sound of the FD15.

But let’s get into the specifics:

Bass:​

The FD15 delivers a textured and resonant bass with a slight mid bass emphasis, though considerably less than other FiiO IEM’s. The bass is never overwhelming, making it suitable for those who prefer a balanced sound signature. While not exactly Harman there is a separation between the bass and the midrange making both clearer. So, songs like Bjork’s Hunter still has a driving bass thump but left enough detail to not overwhelm the song.

Midrange:​

Clean and detailed, the midrange is slightly forward, providing clarity and speed. Vocals are reproduced with sweetness and precision, making the FD15 suitable for vocal-centric genres. The upper midrange is energetic but remains controlled, avoiding the harshness often found in other IEMs.

For me, the midrange is the star of the show with the FD15, I found the FD15 tonally very accurate, vocals and acoustics instruments sounded appropriately and slightly forward in the mix. Once I find a midrange focused IEM ( like last year’s Kiwi Ears Orchestra Lite) I usually spend some time listening to lots of tracks that I know can tease out the subtlies of that tuning so with this IEM with lots of classic 1970’s tracks from people like Nick Drake (with the gorgeous orchestrations), Elton John ( for the
Piano centric tracks) and some classic Bowie (like ‘Life on Mars’) - all these midrange centric tracks sounded fantastic with enough details to really pick apart these classic recordings.

But it would be a perfect tuning for most genres of music, but if you are a ‘basshead’ then this is not the tuning for you.

Treble:​

The treble is smooth and well-extended, with a bright yet non-sibilant presentation. I would say the Treble sounded appropriate giving instruments an accurate tonality but not in an overall distracting way (that you can get with some IEM’s in this price range trying to justify their ’technicalities’). This is probably the weakest part of the FD15 and stops it from having a flagship level sound but at this price it is still excellent treble.

Note: The red tuning nozzles allow for some customization of the treble response, lower its response a little.

Soundstage and Image:​

While the soundstage was not that wide as some flagship models I thought the imaging was tremendous with FD15, that midrange clarity means you can separate out individual instruments with a fantastic sense of depth. I got the feeling from orchestral music, that you can clearly hear different notes from the piano in slightly different distinct places within the soundstage.

Specifications and Measurements​

Here are FiiO published specifications:

Measurements​

These measurements were taken with my 711 clone coupler and are available on my measurement DB here

Frequency Response​

Here is the frequency response, the overall frequency response is balanced (with less sub-bass) mostly aligned with a slightly relaxed treble and a little (though less than usual) mid-bass emphasis, but for me the most obviously aspect of the sound was that upper midrange / lower treble balance:



As you can see in this comparison this is very similar to that Kiwi Ears Orchestra Lite presentation:



I was a little suspect of my own measurements, so I actually checked Gizaudio measurements of both these IEM and they are mostly similar:



Here is the channel balance, I actually measured this with the provided ‘foam’ ear tips which have slightly relaxed treble but I believe this is the relative change you can expect with the ‘Red’ nozzle:

Distortion​

This shows well controlled distortion ( less than 40dB ) even when playing at over 90db.

Group Delay​

For those interested this is the group delay:

Some Comparisons​

As I mentioned, earlier when I started my subjective listening I was immediately impressed with the midrange and the imaging provided, providing a very similar sonic profile to one of my favourite IEM’s from last year the Kiwi Ears Orchestra Lite. My 2 minor complaints with the Orchestra lite was sub-bass was a little light and as an all BA design there was a pressure build up requiring some ‘adjustments’ every so often during long listening sessions especially out walking with that IEM. The FD15 has better bass and given it’s a DD design, it does not suffer from any pressure build up, so I was very happy with this IEM for very long listening sessions.

Another IEM in the $100-$200 range, that I have recently reviewed would be the Aful Explorer and while I loved the Explorer also, I found the FD15 is better, with better packaging and an overall better treble, where the Explorer had some weaknesses. The Aful Explorer does try a slightly different tonality tilt (more bass / less treble) in the frequency response which itself is interesting but may not appeal to everyone.

One other comparison, though unfair given the price differences, is with the Truthear Zero Red (since it is also a DD design), while that also has an excellent tuning, there is no comparison with the FD15. In a comparison the Zero Red just seems ‘cheap’ and it’s large shell is not as comfortable as the FD15, I would also take the FD15 over the Zero Red in just subjective listening but the Zero Red is also very pragmatic and a great IEM for its price.

Here are the frequency response comparisons of these IEMs:

Rating​

I have given the FD15 a 5-star pragmatic rating. I think this FiiO is the most pragmatic IEM they have ever produced, it sounds great, comes in a great package with great accessories and it’s extremely comfortable. I think for the price you are getting an amazing IEM, and it is hard to believe it is a single DD configuration.

Conclusion​

The FiiO FD15 is one of the best mid-fi IEM’s you can get, offering a well-rounded audio experience with excellent all round sound signature. Its build quality, generous accessory package, and innovative design elements like the Tesla valve make it a very strong contender at sub $200 market.

It gets a big recommendation from me, if you like a balanced sound from an excellently designed, quality IEM the FD15 is a great buy at its price.

FiiO FD15

Configuration: Single Dynamic Driver
RRP: $149

Introduction

FiiO don’t need much of an introduction, a solid staple in this hobby for many years now with a significant line-up of products ranging from IEMs to DAPs, cables to desktop audio and lots in between. I have personally owned a number of products from FiiO over the years and once-upon-a-time worked as a distributor for some early iterations of their DAPs.

I recently reviewed the excellent FA19 which is a 10x BA set that retails for $999, now time to take a large step down from a price perspective to their latest single DD offering, the FD15. FiiO provided me with this set free of charge in exchange for a review – as always, all thoughts are mine, all photos are mine, and the contents of the review have zero input from FiiO. The FD15 is available from all of the usual FiiO stockists... a quick Google will find your closest option.

Just to note also, single dynamic drivers have a special place in my heart/collection, as typically the humble DD is my preferred configuration – regardless of the logical ‘limitations’ bestowed on having only one driver doing the job, versus several and in various types. There is something magical about a DD to my ears, and I often think this is due to the familiarity I guess of 2-channel stereo systems from over the years, and indeed going back to listening to personal stereos from the 80s onwards.



About FiiO (From their website)

FiiO Electronics Technology Company, Ltd., or simply FiiO, is a Chinese electronics company founded in 2007 that primarily manufactures audio equipment. Its products include portable music players, audio amplifiers and DACs, earphones, as well as various cables and accessories.

A Bit About Me...

I worked in the consumer electronics industry for a large part of my career and have been passionate about music and technology for as long as I can remember. Even as a small child, I would ask my mum to put records on the turntable (Abba, Supertramp, and Planxty if anyone is curious).

My music preferences are very varied—anything from classical to techno, indie rock to jazz, and everything in between. In my early teens, I was a big fan of bands like The Cure and The Smiths (still am all these years later). I was bitten by the dance music bug in the early 90s, becoming passionate about genres like techno, house, trance, and IDM. I amassed a huge collection of records and CDs, DJing at various parties and occasional pirate radio station slots. Although it remained a hobby, I still own thousands of records, and my trusty Technics 1210 turntables are still going strong 30 years later—a testament to Japanese engineering!

I am not a professional reviewer, just an enthusiast who loves music and the devices we use to listen to it. Over the last few years, I have become obsessed with IEMs and related gear. I've bought and sold many, and kept a select few—ranging from the $20 Moondrop Chu to kilobuck sets like the Aroma Jewel, Oriolus' infamous 'Traillii,' UM Mentor, and various beloved single DDs. Through this exploration, I like to share my thoughts with the Head-Fi community, hoping they might be useful to others. However, remember that this is a highly subjective hobby, and your mileage may vary.

While I've been fortunate to own and try a variety of the TOTL sets on the market, I honestly enjoy lower-priced sets as much - especially as the gap continues to close, many much cheaper sets now offering significant value and further driving diminishing returns.



Specifications

Frequency response: 10Hz-40kHz
Impedance: 32Ω@1kHz
Sensitivity: 112dB/mW@1kHz
Cable: MMCX / 4.4mm & 3.5mm modular connectors

Unboxing & Accessories



The unboxing is as I have come to expect from FiiO, where the brand theme is consistent and offers a pleasing experience… that being of course for those who care about the unboxing – a huge part for me, and something I often make a bit of a ritual of by making a cup of coffee, or pouring a beer/glass of wine, depending on the time of day... it was actually green tea today...




Accessories

As always with FiiO, you are treated to a wide plethora of accessories to include:

• Huge selection of tips to include silicone in various tuning iterations
• MMCX removal tool
• Cleaning brush
• 4.4mm and 3.5mm jacks
• 2x tuning nozzles
• Box - I can't call this a case, nor is it practical to use as one

Cable

The stock cable is reasonably thick and has a bit of weight to it, a touch too much for me if I were to use out and about, but I do prefer as thin and light as possible for out walking for example so take this as a subjective position. The MMCX connectors are very secure but still allow to swivel so as to get a better fit around your ears. As always with FiiO, you get a high-quality modular system to choose either 3.5mm or 4.4mm. It has a nice soft rubbery finish and not much in the way of microphonics.





Design & Fit

The shells are relatively small and finished to a premium level. The medical-grade stainless steel feels robust with a nice bit of weight and once I found the right tips, stay securely in my ears. I owned the FD7 about two years ago but had to return them due to an edge that created discomfort even in short sessions, thankfully no such issue with the FD15… and indeed it was a shame about FD7 as they were a beautiful sounding IEM that would no doubt still be rubbing shoulders with the many single DDs I cherish in my collection.





Listening Impressions

I read a bit of a debate online recently about the term ‘musical’ or ‘musicality’ where the original poster felt it wasn’t very useful as a term, of course some debate ensued which was interesting to read – as with anything, we all have our personal opinions and I do find a place for the description in the hobby, likewise the other direction which is more technical, and at most extreme – maybe even clinical, whereby a set is incredibly technical, but possibly devoid of a musical emotive engagement. I think it’s useful when describing a set to give a sense as to the direction in leans, and in the case of FD15, it’s very much on the musical/emotive end of the scale.

Most of my listening over the last few weeks and in preparation for this review has been with the Sony ZX707, and all via local FLAC files.

Bass

While the bass quantity isn’t huge, the quality is impressive – its snappy, visceral, and has a nice authentic timbre. If you are a bass-head, or even if bass quantity is a massively important attribute from an IEM, I would say best look elsewhere. Sub and mid-bass are quite balanced, no real emphasis on one or the other.

Mid-range

The star of the show with FD15 to my ears is very much the mid-range… lush, warm, smooth, highly emotive and with a robust dome-like presentation. While forward, it doesn’t sound artificial and there is good clarity throughout. The upper mids are relatively relaxed but still give decent energy to strings, vocals etc when called for - I have had a small number of close calls with upper mid energy almost being excessive however... I do emphasise the 'small' though.

Treble

Treble is quite relaxed and I’ve not had any issues with harshness. The relatively balanced theme is again apparent, but still allowing the mids take centre stage. There is enough up top to provide a sense of air, and also not subdued to the point of sounding congested. The clarity of tuning is evident all across the FR.



Technical

As noted, the FD15 for me is a more emotive and musical leaning set. It’s clear to me that FiiO tuned in a way that basically anyone can at least enjoy, and possibly love depending on what you are looking for. The large 13.8mm driver can certainly deliver though in terms of perceived stage size and the general clarity does give a good sense of imaging and layering… just don’t expect the most pinpoint or indeed extraction of the most minute details.

Test Tracks

As always, I am choosing a selection of tracks from my DAP and all are local files in FLAC format. Where possible I link to Bandcamp but otherwise YouTube.



The Flying Mars – The Dance of the Secret Monkey (psychill/dub)



This first track has absolutely impeccable production and mastering and FD15 does a great job of presenting an immensely captivating and immersive experience with those beautiful mids. This genre has a lot of low-end emphasis which would lead me to choose another set to best capture the deep sub-bass, but a nice performance regardless. Percussion is crisp and detailed, and the stage extends out to an impressive width beyond my ears.

Destroyer – Chinatown (indie/rock)



This is a slightly older recording, and while the mastering is pretty good, it doesn’t have a hi-res production level. The timbre sounds really nice here, be it guitars, vocals or percussion – the sax makes itself know every so often and sounds really beautiful. Male vocals maybe a touch thinner than I might like. For the most part, an excellent job and one of these moments where I need to remind myself I’m listening to a set that sits around $150 – bloody impressive.

Idles – Scum (punk/rock)



An old favourite of mine to test an IEMs ability to handle complexity without becoming a total car-crash. I hadn’t listened in a while but saw them playing when watching Glastonbury on TV recently. They pass the test anyway, the climatic moments of the track reach a point where they almost become a problem but just fall short – to be fair though, that’s typically the case with IEMs when they pass the test – it’s a pretty fast pass or fail, and a fail is usually where there is too much upper energy and more resolving tuning.

London Grammar – Oh Woman, Oh Man (rock/female vocals)



Oh wow… yes indeed, here again is where those beautiful mids shine – the vocals are forward, yet intimate and captivating – they position themselves absolutely smack-bang in the middle of my head, and step forward. Piano is ethereal, percussion is airy and authentic. A really impressive job here.

T.Power – Police State (Drum & Bass)



A remastered, 24-bit reissue of the classic from the 90s. Drum & Bass another favourite genre of mine to put a set through its paces – always curious to hear how low it can go, and whether it survives the frantic percussion pace and complexity. Surprisingly on the first element of the test, the sub actually sounds pretty decent and while not chest-rumbling levels, it does occupy a nice amount of my skull. Percussion is rendered well and the driver has no problem keeping pace without sounding congested or harsh.

Mykja – Nyr Scent (ambient)



Almost every time I write a review, I stumble across an album I’ve neglected for way too long – absolutely the case here. This track features on the stunning ‘North Paths’ from 2017, on the always excellent Faint label from Spain. While broadly ambient, it does have a lot going on with various intricate layers developing throughout the track, to include a pulsing kick drum that sounds like a beating heart when it arrives. The FD15 does a wonderful job of capturing an atmospheric presentation of complexity and splendour, and I could very happily pick up this set again in the future to enjoy this album and others like it – indeed many others on the Faint label alone… highly recommend investigating if you enjoy ambient music and not already familiar.



Conclusion

The FD15 offer an engaging and well-balanced tuning that leans towards the mid-range, creating an emotive listening experience. The large 13.8mm drivers and powerful magnets deliver sound performance that surpasses its price point in my opinion, notably with good imaging, layering, and clear tonality. The tuning is pretty safe and non-offensive, with natural timbre - note occassional upper mid zest, but all of my listening has been with the default silver nozzle (I still need to test the red). Comfort is ensured by small, high-quality shells made of medical-grade stainless steel, and the curved MMCX connectors provide secure and adjustable fit. The extensive selection of tips and essential accessories, along with a good stock cable featuring modular connections really emphasise the overall value. The inclusion of two tuning nozzles allows for customizable sound profiles, adding to the fantastic value at a price just shy of $150... I will at some point try the red nozzles too

Worth noting again that the FD15’s focus on an immersive musical experience rather than technical resolving may be a drawback for those seeking the latter. The prominent mid-range may not satisfy listeners who prefer more bass or treble. While the MMCX connectors are secure, some may prefer the 2-pin option for greater compatibility with existing cables. The lack of a supplied case is I suppose a minor inconvenience, and the small shells may pose a challenge in achieving a good fit for some users… but do try larger tips if you face this challenge!

Overall, I find the FD15 another great set for comparitively low-cost and yet again demonstrates for me that it is absolutely not necessary to break the bank to simply enjoy your music...

FIIO FD15 a balanced natural sound

Disclaimer
I got the FD15 for free in return for a review, I am free to say whatever I want.

All impressions are my own subjective thoughts after having used them for a good time. These are my thoughts at this moment, and as time moves I might change my opinion.
This is also a very subjective hobby where everything from experience, anatomy or age will affect what we hear. Also keep in mind that it is easy to use bold words when talking about differences, while it may be perceived as a small change for you.
While I can perceive something as natural sounding, I do believe we can never get a perfect performance similar to what is achieved live.

Ranking System:
1 Very bad or unlistenable
2 Listenable but not good
3 Average
4 Very good
5 Exceptional or having a special sauce

My rating system highly values what is musical for me, so my rating will always be a subjective opinion.



About me and my gear used for the review

My audio preference is neutral with some warmth, I can also like forward midrange and treble if not excessive. I am a believer in having different tuned gears for different genres or moods instead of chasing the single perfect one.

Main music genres I listen to are metal, electronica, jazz and pop. I am a music lover, and can also listen to almost all the genres out there.
I have been into music gear since the mid 90s, gifted some big speakers at an early age. Then moved more and more into headphones with the Koss Porta Pro and a Sony Discman.
I have also tried playing many instruments over the years from piano to sax and have a feel for what's a natural tone, but not the biggest patience in learning to play.

My current favorites in Headphones are ZMF Verite Open and Beyerdynamic T1 G2.
My current favorites in IEMs are 634ears LOOK 2-TX02 and Campfire Audio Bonneville.
My current favorites in Earbuds are FranQL Caelum and Venture Electronics Zen 3.0.

Gear used in the main rig is Denafrips Ares 12th-1 DAC together with the Topping A90 Discrete headphone Amp. I also have a Schiit Lokius I can swap in if I want to do a little analogue EQ.
Portable gear being HIBY R8 II, with some dongles like HIBY FC6 and Colorfly CDA-M1P.



So what is the Fiio FD15

FIIO is one of the largest audio brands in the world within portable audio, they were established in 2007 in China. The FD15 is their newest IEM in their FD series that uses dynamic drivers and focuses on IEMs for vocals and pop music, this is the successor to the FD5 from 2020. They have cut the price in half and provided a more mature tuning versus the FD5. From then they have been able to cut the cost, while still having the same quality. Still the premium stainless steel shell, and swappable hardware on the cable.

They are using a large Magnalium + DLC (close to pure beryllium driver) 13.8mm driver in the FD15, together with a very strong 1.5T magnetic flux magnet. They have also increased the voice coil from FD5. All of this just means they have been able to make a better sounding and technical IEM.

There is also much thoughts done into how they have made the acoustic chamber of the IEM






The packaging is decent without being overdone, you get a written quick starter guide that I don't full see the reason for in our day where we try and reduce environmental footprint.




The shell is small and solid with stainless steel, in a universal design. For being this type it's good on the ergonomics. Also since it uses MMCX that makes it easier to swivel the cable for better fit.

The black version I have here is a fingerprint magnet, and I suspect it's also easy to get scratches over time. Personally the design is nice, but the silver would be better as the black hides the small design features of the shell .

Nozzle is exchangeable, and is good length.



The accessories are good with plenty of tips to choose from, also a nozzle to change the sound a little. The only bad accessory is the acrylic storage box.



The stock cable is excellent, with angled MMCX connector for better secure fit. The cable also sound very good as stock cable, and I couldn't even see any need changing to a EA Cadmus 8W.
You also get a modular jack to change from 3.5mm single ended to 4.4mm balanced, and it uses a screw mechanism to make it secure.



Timbre

First off, what is Timbre?
From the Wikipedia:
The Acoustical Society of America (ASA) Acoustical Terminology definition 12.09 of timbre describes it as "that attribute of auditory sensation which enables a listener to judge that two nonidentical sounds, similarly presented and having the same loudness and pitch, are dissimilar", adding, "Timbre depends primarily upon the frequency spectrum, although it also depends upon the sound pressure and the temporal characteristics of the sound"

First minutes of trying a new set of gear, what I always listen to is how natural and musical it sounds. Much of this goes down to how I perceive the Timbre.

The timbre is very natural and full sounding on FD15, no veil or lack of weight in the music.

Going to use the ranges here in review:





Details and soundstage

While not being the most resolving DD I have tried, it's really good for the price point. Some of this due to all the textured details in the midrange and bass, good at showcasing small nuances with maybe only lacking some detail in the upper treble. It has some softness to the sound, meaning transients is a little rounded.

Soundstage is average in size both for depth and height, everything is positioned from my ears in a stage around the head with some forward projection. The imaging and separation is excellent, and does sound better than the competition I have heard at the price.



Bass

Bass is really well done, has both a good mid bass punch and deep rumbly sub bass, the bass decay sound very natural. As the FD15 is what I call natural W shaped, the bass quantity is in harmony with the mids and treble to not sound too bassy.

Bass is actually really well done on FD15, I think they have made good use of the large driver without making it loose. Playing bass heavy music is really fun and bassy, while when playing acoustic music like jazz it sounds neutral and warm with an organic texture.



Mids

Midrange is full sounding and clean, this is what I would call natural midrange. But when we compare to most other single dynamic drivers this sound fuller, so the midrange is more forward. But I think the problem is more with how most sets have recessed midrange.

The low midrange has some added thickness to it, not too much so it doesn't sound muddy or husky. If you come from a set with clean bass tuck this can sound unnatural for you, but again i firmly believe the bass tuck is the wrong type and mids need some thickness to sound real.

Upper midrange is not overly bright like harman, instead it has a QDC style of increasing early but with less of a peak. In return it is detailed in the presence region without getting shouty or metallic. Its equally good for male and female vocals, same for instruments being more dark or bright.



Treble

The treble has decent air and clarity and makes it sound realistic, but it's not perfect. If you look at the measurement, it has some treble spikes. Usually I am not that sensitive to this, but here I have noticed it on some music where it sounds brighter.

Most music is good, and its very specific music like J-Pop or brighter females that can get a sharper tendency. Also some rock and metal can get a little more crisp cymbal hits due to this.
Almost no pop I listened to had this problem, same with stuff like electronica or hip hop.



Synergies

Most of the listening I have done with their new dongle FIIO JA11, a small alternative to the apple dongle with better sound and built in PEQ through app.
This was a good combo to be listening with, while not the most resolving it was more than decent and sounded full.

What I liked the most with FD15 was using R2R through my desktop setup or just using the HIBY FC6 dongle, this just enhances the already natural sound with a little more fullness to each note.

Stock cable is also very good and its nothing wrong with it, tried it short with Cadmus 8W and couldn't see any point using it.

Must admit I have not used the FIIO silicon tips, I have used only the Divinus Velvet. Not that the stock tips are wrong, there is plenty to choose from to get full sound with a good seal.



Comparisons

When evaluating the sets I use each of them over longer periods and also some shorter sessions swapping back and forth, it takes a long time and is not done in one sitting. The most critical comparison is done on my desktop setup that is highly resolving, with volume matching to take away loudness variance.
I have decided on using two other single dynamic driver IEMs, one slightly more costly and the other cheaper.

The spider chart is slightly exaggerated on some points to show differences.





Oriveti OD200 - 9.8mm beryllium coated dynamic driver

OD200 also has nice packaging and accessories, the shell is also premium. The OD200 is actually one of the most comfortable IEMs I have used at a lower price bracket, FD15 cannot compete against it here unless you have very small ears.
Both have changeable nozzles, on both I have been using the warmest combination on both. So silver on both the OD200 and red on FD15.

This is more of an L shaped sound with less upper presence and treble, overall thick and bassy. The technicalities are not its strong suit, and you do hear less details in the music than with FD15. The resolution is not due to the driver, it's mainly down to the tuning.

Bass is more thick than FD15, both have similar denseness to it with the FD15 just more textured. The speed of the decay is very similar, so the bass slam is similar in how hard it hits. OD200 lacks good sub bass extension and focuses much more on mid bass, here FD15 is much better balanced between the two.

OD200 have more bass bleed and sound slightly muddy due to this, music often sound more thick in the midrange. This would be okay if the OD200 had good upper clarity, but this is lacking on the OD200 so it sounds much less clear on music than FD15. This affects both the upper midrange and the treble, with less air also making music slightly dampened.

What OD200 does excellent is make no music tiresome or sibilant, it has a more bassy and thick sound signature instead.



Simgot EA500LM - 10mm lithium-magnesium alloy dynamic driver

The EA500LM is half the cost of the FD15, and one of the most technical IEMs for the price with a premium shell and decent accessories. Both have a universal design on the shell, the FIIO is a little better for me since nozzles can sit more securely. While the rounded edges on EA500LM are better for long term comfort, both have a premium feel to them. Both have changeable nozzles, on both I have been using the warmest combination. So red on both the EA500LM and FD15.

The FD15 sounds both thinner and more sharp, with a less accurate and natural timbre to me. The sound is more V shaped versus the FD15 being more natural with a warm midrange w signature. The FD15 is more technical to me, has that little extra over the EA500LM in microdetails.

On paper the EA500LM has more bass, but it's not showing in most music. Think this is because EA500LM has very fast decay, and the upper midrange/treble takes away some of the bass weight. This makes you play the music on lower volume with EA500LM, while you can push it higher on FD15. Both texture and punch is better on FD15, not that EA500LM is bad either.

The midrange is a little behind the bass and treble, opposite of how FD15 is. While both being very detailed in the midrange, the EA500LM sounds a little thin and metallic. There can also be some sibilance on brighter singers or instruments with EA500LM, also one of the reasons why I play it with more of a low volume.

The treble is decent on both, and while the EA500LM should be more airy on measurements I dont really hear the difference. Just that FD15 sounds a little more natural and less bright, if this is due to upper mids or treble is tough to evaluate.



Music

https://tidal.com/browse/playlist/ad7bbfa3-2067-4235-b2ed-f5a3fb53ff28

When comparing FD15 to other sets I have used some of the tracks in the playlist and more. The playlists are quite large now, and need some editing.

I'll also mention some tracks with FD15, my own listening being with Bandcamp or Tidal. Tidal added some time back the possibility to share music with the option to choose other streaming services also.


https://tidal.com/browse/track/267372746?u

Apostrophe - Hypnopaedia

My newest track to hear after brilliance and airiness in the music, the mid treble peaks help push more shimmer to the music here. Without it would have sounded a little shy on the airyness.
This can get tiresome if the treble is poorly done, and FD15 behaves well while not being as good as the very controlled Project M I recently reviewed.


https://tidal.com/browse/track/349903243?u

The Omnific - Base Camp

If you like prog rock and bass this is some of the best, the group uses two basses and a drummer. And with that alone it sounds so full and fun on FD15, also a very good track to test for how good the low midrange and bass is.Been listening to this album a lot lately, and was probably the first album when I tried FD15. Heard immediately that FD15 has a good bass texture with natural speed, also an warm but clean midrange that's not too thin or thick.


https://tidal.com/browse/track/345859574?u

Fink - One Last Gift

His latest album is great, has a folk and Americana vibe with some indie. Good mix of clarity and fullness with FD15, his voice is neither too thick or thin and is what I think sounds correct for this. Good separation and clarity between his voice and instruments, the guitar sounds very organic and clean. For example listening to the OD200 here the music drowns out some of the guitar as its not as open sounding.


https://tidal.com/browse/track/337120918?u

うぴ子 - CROW

A Japanese singer with a quite rare voice in Japan, she sings much darker than most. FD15 is good at capturing all the nuances in her voice, the less peaky upper midrange makes it sound less aggressive. The low midrange of FD15 also helps it sound a little fuller and more engaging than a typical Harman tuned set with bass tuck.

Still the song is quite energetic and forward, so I can get tired with FD15 on a longer session.


https://tidal.com/browse/track/370637253?u

CHUU - Chocolate

Sugary sweet K-pop with female vocals, lots of mixing and effects blended in. Punchy and vibrant bass line, her voice is a little sharp and shows some sibilance with FD15. Playing with less volume is better, and then it have good balance, clarity to the bassline, voice and rest of the effects.


https://tidal.com/browse/track/349903243?u

Funky Dragon - Who’s There (Smoke Sign & Solaris Remix)

Psy electronic with vibrant and punchy bassline, also quite many electronic elements around the stage. I never thought this, but the tonality on FD15 is addictive with electronica. Enough bass to sound bassy and fun, good amount of clarity and details. The fuller midrange makes it sound less hollow versus something more v shaped.



Conclusion

I have not had that many FIIO products, this is my first one in the last few years.

I didn't expect too much coming into this, and was met with a very natural and rich sounding IEM I really like.

What it does so well is sounding natural without being thin or thick. Enough warmth to be fun for my music, with a good and present midrange that is so often lacking on many sets.
There is also the amount of texture in the bass and midrange, I believe the use of an extra large 13.8mm driver is the reason. The magnet is also having good control over it so it doesn't sound loose, I think this is a thing more should aim for forward using a larger driver.

You also get a very good stock cable with modular jack, also plenty of tips that are of good quality. The shell is in solid stainless steel, and has good balance in the weight not feeling heavy or light.

It's not all praise, there can be some tendencies to sharpness in the treble. For the music I listen to on a day to day basis it sounds good, but when using some of my test music I do notice it.

There is also the use of universal design on the shell, while being small and fairly ergonomic it is not to my preference. Thankfully due to nozzle length and the cable having good angled ear guides it sits very good for such a design.

Going to give it a solid 4 star rating, meaning its very good for the price. Highly reccomend this, excellent value and one my favorite 2024 realeses.

DISCLAIMER

I bought the Fiio FD15 at a discounted price from Aliexpress.

It can be gotten here: https://www.aliexpress.com/item/1005007196989439.html (no affiliate links).




SPECIFICATIONS

• Driver configuration: 13.8 mm aluminum magnesium DLC dynamic driver
• Frequency response: 10 Hz - 40 kHz
• Impedance: 32 Ω
• Sensitivity: 112 dB/mW
• Cable: MMCX; Furukawa monocrystalline silver + silver-plated copper cable; 3.5 mm and 4.4 mm modular terminal plugs
• Tested at: $149.99 USD

ACCESSORIES

Other than the IEM, these are included:

- 2 pairs of foam eartips (M)
- 3 pairs of bass silicone eartips (S/M/L/)
- 3 pairs of balanced silicone eartips (S/M/L)
- 3 pairs vocal silicone eartips (S/M/L)
- 3 pairs of HS18 silicone eartips (S/M/L)
- HB11 storage case
- 2 pairs of tuning nozzles
- Cable
- 2 modular terminals for 3.5 mm and 4.4 mm plugs
- MMCX release tool
- Cleaning brush

For something retailing at sub-$150 USD, the accessory spread is impeccable. Everything that an audiophile needs is covered and it just screams "premium", putting some way pricier sets to shame here.




We have a whole host of different eartips:
- The HS18 tips bestow a warm neutral tonality, with solid fit and seal.
- The "Vocal" silicone tips boost upper frequencies.
- The "Bass" silicone tips improve the lower frequencies.
- The "Balanced" silicone tips are mid-point between the above 2 tips.
- The foam tips enhance isolation, though they compress the treble frequencies somewhat

Do tip-roll to see what suits you sonically and in terms of comfort, fit and isolation.




We have an MMCX Furukawa monocrystalline silver + silver-plated stock copper cable. It is very well-braided and supple, with just a slight smattering of microphonics. There's a chin cinch for added grip.

This cable comes with 3.5 mm and 4.4 mm modular terminal plugs, depending on your source preferences for single-ended or balanced sources respectively. The modules lock with a screw-on mechanism, which prevents the connected DAP or phone from inadvertently dropping out in cases of modular cables without a lock.




Fiio has included a nifty HB11 storage case (https://www.fiio.com/productinfo/974710.html). Made of tough plastic, it can definitely withstand compressive forces. This case incorporates an innovative lego concept, so additional cases can be stacked on top of it. This case even has a handle - this functions like a sock drawer - and the transparent walls allow users to visualize the internals. The HB11 is space-conserving, with a thickness of 2 mm for the walls, and it weighs 118 g, and measures 116 x 72 x 39 mm.

To round off this treasure trove of accessories, we have 2 pairs of tuning nozzles, an MMCX removal tool and a cleaning brush.

The rest of this review was done with the stock cable and stock HS18 silicone tips. No aftermarket accessories were used, so as not to add any confounders to the sound.


BUILD/COMFORT



The FD15's housing is fashioned from medical-grade 316L stainless steel. This is manufactured from a 1400 °C powder metallurgy sintering process which has gone through 10 composite steps. Thereafter, each earpiece is hand-polished and this culminates in PVD electroplating.

The end result is the earpieces being as sturdy as a tank, yet boasting of beautiful curves with an elegant mirror-like finish on a round barrel-like shape. These shells may be scratch or finger-print magnets though, so do baby them with care!

When ordering, one can choose between an obsidian black or silver-hued shell.

Despite each housing weighing 12 g, I found the comfort to be agreeable. The inner aspects have no poky edges, and are as smooth as silk. Fiio has designed the FD15 after collecting ear data, and have specially enforced a raised 6.7 degrees nozzle along the Y-axis for improved comfort and stability.



Honestly, I'm not a fan of MMCX connectors, but the ones used in the FD15 seem to be quite well-implemented, being neither too tight nor too loose. This MMCX housing allows swiveling of the IEM when wearing the FD15, which further improves ergonomics.

Being a vented IEM, the FD15 has average isolation, though the vents aid in soundstaging. I did not encounter any driver flex on my pair.




DRIVABILITY

I tested the FD15 with the following sources:
- Apple dongle
- Cayin RU7
- Chord Mojo 2
- Fiio KA11 dongle
- Fiio KA17 dongle
- Khadas Tone Board -> Schiit Asgard 3 amp
- ONIX Alpha XI1
- Questyle M15 DAC/AMP dongle
- Sony Walkman NW A-55 DAP (Walkman One WM1Z Plus v2 Mod)
- Sony Walkman NW A-55 DAP (Walkman One Neutral Mod)
- Sony Walkman NW WM1A DAP (Walkman One WM1Z Plus v2 Mod)
- Smartphone

This IEM is easily driven, with no hard requirements for amplification.


INTERNALS/TUNING NOZZLES

This IEM's engine is a 13.8 mm Magnalium DLC dynamic driver housed within a closed-back acoustic shell. Fiio utilizes some creative and innovative acoustic technology to improve the final sound:

• A W shaped gasket increases vibration of the diaphragm by 30%.
• A frontal acoustic prism concept uses subtle sound delay and reflections to control phase resonance.
• A 1.5 T magnetic flux is produced by a patented Tesla valve bass enhancement flute system. This is supposed to extend sub-bass reach, and also balances internal and external acoustic airflow; indeed we do not find driver flex on this IEM or a pressure-build up sensation in the ears.

The FD15 has 2 tuning nozzles, which increases versatility and furnishes variations of a warm-neutral tuning:

Graph of the FD15 via IEC711 coupler. The 8 kHz region is a coupler artefact peak.

Tonally, the FD15 is very pleasant with the black nozzle. This warm-neutral signature is balanced and should please most users other than diehard trebleheads or bassheads.

The red nozzle tames the upper mids/lower treble slightly, adding more warmth and note weight, though there is a slight blunting of resolution with this installed.




SOUND & TECHNICALITIES

The following impressions are done with the black nozzle in use.

On this setup, the FD15 is sub-bass focused. Overall bass quantity is a hair north of neutral and this is not a basshead IEM by any means. Extension is not too deep, and there is just a tickle of sub-bass on bassier tracks. However, the FD15 cedes quantity for quality, and we hear a clean and fast bass with no bleed. Texturing is excellent, and can compete with more expensive rivals in this department.

The lower midrange is transparent and of authentic note weight, neither being too thin or too thick. Upper mids hit just 5 dB in ear gain, which translates to non-shouty and smooth vocals. This area is quite crystal-clear and midrange lovers will have a feast.

The FD15 has moderate treble extension, though there is an upper treble roll-off. Thus, it isn't a very airy set for trebleheads. Sibilance is negligible, and it is a great companion for relaxing to, especially on the more sedate red nozzle.

In keeping with its single DD roots, this set has a very natural timbre for vocals and acoustic instruments. No complaints on this front.

The FD15 is more of a musical IEM than a highly technical or analytical one. The note edges on the FD15 are blunted to relief harshness. Technicalities are above average but not class-leading amongst other $100 - 200ish single DD sets. Soundstage is commendable and goes beyond the ears with decent imaging. It isn't the most micro-detailed pair and instrument separation can get a tinge smeared with very complex tracks.


COMPARISONS

The Fiio FD15 will be compared against other $100 - 200ish single DDs. All-BAs, hybrids, and planars are omitted, as they have their own pros and cons due to the different transducer types.



The following impressions are done with the black nozzles installed.

It has to be said, all of the 3 single DD types described here are more expensive than the FD15, so the FD15 is actually disadvantaged. However, these 3 IEMs are the usual gatekeepers for the $100 - 200 single DD bracket, and readers will surely ask how the FD15 stacks up against them. FWIW, for other $100-range single DD types like the Moondrop KATO, the FD15 destroys it, so it is a complimen that the FD15 is pitted against pricier contenders in a small tier above it.


Oriveti OD200


Graph of the OD200 via IEC711 coupler. The 8 kHz region is a coupler artefact peak.

The OD200 has two tuning nozzles. However, one is practically unusable, with a huge 13 dB pinna gain being an ice-pick in the ears. Most audio forum members are stuck with the other more relaxed nozzle, though we lose resolution compared to the other shoutfest nozzle.

The OD200 with the silver nozzle has a thicker note weight, but has inferior soundstage, imaging and micro-details.


DUNU Falcon Ultra


Graph of the Falcon Ultra via IEC711 coupler. The 8 kHz region is a coupler artefact peak.

The Falcon Ultra has 2 tuning nozzles - one gives a Harmanish profile, while the other is more laid-back and bassy. With the Harman-like blue nozzle in place, the Falcon Ultra does have a peakier upper mids and more bass (it can be somewhat fatiguing for the anti-pinna gain gang).

The Falcon Ultra has a smaller soundstage, but has better micro-detailing and imaging.


Simgot EA1000


Graph of the EA1000 via IEC711 coupler. The 8 kHz region is a coupler artefact peak.

To be pedantic, the EA1000 actually has an added passive radiator to furnish bass heft, so it isn't a pure single DD. However, it mostly functions as one, and is the benchmark to beat at this price range.

FWIW, the EA100 has 3 tuning nozzles on offer, to bestow a spectrum of bright Harmanish tones. All nozzles confer the classical boosted upper mids of Simgot's house sound, and the EA1000 is much more brazen in the upper frequencies, with more sibilance and fatigue on display.

The EA1000 however, has improved micro-detailing and imaging, though it loses to the FD15 in soundstage.


CONCLUSIONS



In a sea of Harman-tuned fare, Fiio has taken a different approach with the warm-neutral FD15. I have to say it is quite a successful venture, with this single DD delivering a musical signature that is euphonic and pleasing. Timbre is natural, and there is an added tuning nozzle to adjust the upper mids/lower treble to your preferences.

Bassheads will definitely yearn for more bass kicks - no pun intended - but the FD15 goes for a quality bass, espousing a fast and clean lower-end that has no bleed; bass texturing is also a highlight on this set. The midrange is transparent without the usual steroid-infused overly-zealous pinna gain seen in CHIFI gear, and sibilance is quite subdued.

The FD15 is not the sharpest tool in the shed when it comes to sheer micro-detailing and resolution, but soundstage is quite expansive, besting some touchstone single DDs like the EA1000 and Dunu Falcon Ultra in this arena.

The FD15 also comes with an impeccable set of accessories, and sports a tough yet elegant mirror-like finish (this may be a scratch or fingerprint magnet though). It is easily driven even off the weakest of sources, so there is no worry for amplification.

In a nutshell, the FD15 is a musical set that is competitively priced, and is actually cheaper than the gold-standard midFI single DD duopoly of the Falcon Ultra and EA1000. In an era where companies are chasing exotic planar quad-brids and multi-driver behemoths, the FD15 harkens back to the simple golden-age of single DDs where tonality and timbre are the first priority. This is palate cleanser of sorts and should be a consideration for single DD lovers.

Disclaimer: FiiO provided me with a review unit. All thoughts and opinions are my own.

Introduction​

FiiO has been going back to step up their IEMs recently after a string of great releases in the DAP and amp department. Now, we started to see the “1” series of the IEMs, starting from FD11, FH11, FA19, and FX15. If you’re unfamiliar about the naming scheme, you can refer to this; essentially this means that they are the refreshed/upgraded version of an existing product line. This now leads to their newest release, the FD15 ($150), which is the upgraded version of the very popular FD5.

The FD15 is now sporting a different diaphragm material (magnesium-aluminium alloy) from FD5 (beryllium), with a 40% larger dome, longer coil, and stronger magnet (up to 1.5 Tesla; it actually moves the entire IEM if you put them too close to each other). According to FiiO, these would improve dynamics and lower distortions, but of course the final say should be in the listening experience. Let’s get into it then, shall we?

Packaging, Build & Specifications​

Driver configuration: 13.8mm DLC gasket + Magnesium-aluminium alloy (Magnalium) diaphragm
Frequency Response: 10-40kHz
Sensitivity: 112dB/mW @ 1kHz
Impedance: 32Ω
Cable: 1.2m Furukawa monocrystalline silver + monocrystalline silver-plated copper
Connector: Standard MMCX
Plug: 3.5/4.4mm modular plug

The packaging of FD15 is pretty generous. Included in the box, other than the IEMs and the cable, there are 5 sets of various eartips (including the HS18), the HB11 stackable storage system, MMCX remover tool, cleaning brush, and a set of alternate modular nozzles (red).



Speaking about the eartips, they came in different types: balanced (white translucent ones), vocal (white translucent with red shaft), bass (gray translucent with red shaft), foams, and the HS18. I did a quick comparison between the balanced, vocal, and bass tips (skipping the foams and HS18 due to fitting issues and comfort). The vocal and balanced tips are very similar to each other with the shape being almost identical; the vocal tips have a slightly softer dome, but the sound of these two is almost identical to my ears. The bass tips are similar to the AET07 and it does add a bit more low end punch.

The storage case (HB11) is good for static storage, it is not really for travel as it is actually a mini drawer with a Lego-like attachment system. I wish they used the older Pelican-like case like the one included in the FH1s.

I also wish that they provided a sort of screw-in holder for the extra nozzles, currently they are held in a thick plastic sheet with a small cutout, making it hard to store and take out. The nozzle is pretty good quality and does not unscrew easily.

The cable is actually the same as the LC-RC 2024 upgrade cable. It is excellent with little microphonics and neat 4-wire braiding with Furukawa pure copper material. I personally prefer the more common 0.78mm 2-pin connector, but the MMCX used by FD15 is pretty solid and does have some resistance to spinning. The modular connectors come with 3.5mm and 4.4mm plugs (no 2.5mm) which connect to the cable with a screw-lock system, which is my preferred modular cable implementation

The IEM housing is made out of 316L stainless steel for an improved corrosion resistance and strength. Despite that, the IEM itself isn’t that heavy, but you do feel the heft after wearing it for a while. The heft does increase the tendency for the MMCX to spin around more, but it also does make it feel more premium.

The most interesting thing in the housing is of course the “Tesla Valve” located in the vent, called the FTBS (not sure what it stands for). For those who are unfamiliar with the concept, a Tesla Valve is a one-way valve without any moving parts invented by Nikola Tesla. The valve will allow undisturbed flow of fluid from one direction, but greatly reduce the flow in the opposite direction. In FD15, the valve is positioned in the way where air can enter the IEM housing freely, but resist the air flow going out of the housing. This allows for a more powerful air pressure in bass frequencies without causing any too much pressure build up by still allowing some air out, theoretically resulting in better bass extension according to FiiO.

Overall, while I have some reservations about the storage case, the IEM is very well-built, the cable is very nice, and the other accessories are generous.

Sound Impressions​

Sources: FiiO KA11, Onix Alpha XI1, Xduoo XA-10, FiiO M23, SMSL H300+D300 stack
Setup: Stock balanced L tips, stock cable with 4.4mm termination (if possible), black nozzle
Music Sources: Youtube Music, Tidal Masters, Apple Music Lossless

The IEM has undergone a 24-hour burn-in at a medium volume prior to the review.

Listening impression is a very subjective experience depending on individual ear shape, choice of eartips, music library, and personal preferences, so your experience may vary. I personally listen mostly to pop, jazz, some rock, and very limited metal.

Measurement is taken with IEC711 clone coupler with foam tips

The tuning can be briefly described as U-shape. The vocal is left pretty clean and relatively undisturbed by other regions and I would describe the overall tuning to be pretty versatile and all-rounder.

The bass quantity itself is pretty modest, certainly won’t make bassheads salivate. The Mg-Al alloy diaphragm is usually fast, lean, and very textured. The addition of the Tesla valve system does add some additional texture to the bass to make it resonate just a bit longer (sort of reminding me of the passive radiator implementation in other IEMs). Each bass note has a tasteful trailing tail that lingers a bit longer adding a sense of grand-ness. There’s a slight rolloff in the subbass, which contributes to its more realistic bass expression.

The midrange presentation is pretty clinical. Vocal is slightly forward, with good clarity and speed. Both male and female vocals are well-reproduced and sweet. The midrange does have some Harman-ish neutral quality to it, but a much tamer upper midrange/pinna gain. I find the upper midrange generally detailed and energetic with the black nozzle, while on the red nozzle this part is slightly more subdued without losing much detail.

The treble is quite airy and well-extended. There’s no sibilance nor sharpness, but there is quite a bit of emphasis in the lower treble. To note, both nozzles have more or less the same treble; the nozzles seem to exclusively affect the upper midrange. For the price point, the treble is very competitive. Overall, I find the treble response to be pretty textured, not overly-smoothened, and generally pleasant.

Technicality-wise, I find the soundstage to be relatively spacious with decent separation and good resolution. Imaging is not its strongest suit, but the layering is pretty well done. Timbre is leaning towards natural and realistic. Dynamics are great, owing to a very agile driver. Overall, I find the technicalities to be very competitive within the price range.

Bass: Textured, resonant, midbass-leaning, grand
Mids: Clean, detailed, sweet
Treble: Smooth, bright, well-extended, non-sibilant
Technicalities: Spacious soundstage, good resolution, decent layering and imaging, natural timbre

As for the pairing, I find it to be pretty easily driven by most modern sources, but it does benefit from more powerful sources. I prefer a more coloured source (especially warmer ones), like the Xduoo XA-10 and Onix Alpha XI1.

Select Comparisons​

NOTE: I have very limited experience with the FD5 and thus very little memory about it, so I won’t be making a direct comparison with it.

Simgot EA1000 ($220):
When I was listening to the bass of FD15, I really am reminded of the passive radiator-equipped bass of EA1000; both sounding grand without being necessarily reflected in the graph. The mids are more neutral on the FD15 and more energetic in EA1000. Resolution is slightly ahead with the EA1000 but it is closer to the sibilance area depending on the tracks, while FD15 has safer upper mids. I would recommend FD15 to listeners who are more sensitive to treble.




Moondrop Starfield 2 ($109):
Between the FD15 and Starfield 2, the biggest difference would be in the overall texture. Starfield 2 is very lean, tight, fast, and bright. With FD15, the tone is relatively more relaxed but still keeping some of the details and speed. Technicalities are slightly better on the FD15. The Starfield 2 is way brighter compared to the FD15. For trebleheads, the Starfield 2 might be a better option, but for most listeners, FD15 is easier to like. Additionally, surprisingly the bass in FD15 has more oomph than the Starfield 2 despite being lower in the graph, probably courtesy of the Tesla valve.

Conclusion​

FiiO FD15 marks a strong entry into the super competitive mid-fi single DD market, especially with the novel concept of Tesla valve, as well as solid build quality, nice cable, and ample accessories. I think it is an easy recommendation at $150 range if you’re looking into a single dynamic driver IEM.