Thoughts on FLC8S


(edited slightly and reposted from head-fi)

tgia note: it’s very fitting for the first post to be on my favorite IEMs to date.


The FLC8S, from FLC Technology, is a dual BA/single dynamic hybrid released this year. Its biggest selling point was the 36 different sound signatures that you could switch between by way of nozzles and filters. They haven’t received much attention, even though I feel like they’re one of the best universal IEMs I’ve ever listened to. As such, I’ve decided to write a review on these, so that more people can get to know and appreciate this pair of amazing IEMs.

Setup used:

Portable: LG G4 –> Dragonfly 1.0

Desktop: MacBook Air –> Objective2 Combo

Appearance, Build Quality and Fit

I don’t have the packaging with me right now, so sadly I don’t have pictures of the box. It did come very nicely packaged with a three-layer intricate box. There was a little plastic bag of tips in 4 sizes (XS, S, M, L) with the clear M tips on the headphones. Other accessories include a pair of tweezers (which are actually not very useful), a screw-on metal hard case that seemed very sturdy, an airplane adapter, cleaning tool, and – most importantly – the keychain with all the filers and nozzles.

The FLC8S are not black as suggested by a lot of pictures online; instead, they are slightly blue in color.The IEMs themselves are surprisingly small. Even though they look plasticky, they seem well-made. Another bonus is the removable cables (I have not tried pulling them out yet – a brave soul who gets these headphones can try!). The cable’s braided and seems pretty sturdy, even though the upper part seems a bit thin. It’s slightly bouncy and microphonic, but I don’t find it a major problem for me. One thing I’d like to mention is the memory wire portion, which created some troubles for me initially – I’ve been spoiled by the nice cables on the Westone 4 and thus found the memory wire pesky, as it prevented me from getting a secure over-the-ear fit and the headphones would move easily when I was walking. Eventually, though, I got used to it. Another problem is the non-angled nozzles, which may be a problem for some people. I personally found it fine but my friend did complain that it was slightly uncomfortable when he put them on, so that’s also something to consider. Besides these two minor points, though, the fit is very nice, due to the small form factor. They’re also very light, which helps a lot in securing the headphones.

A major selling point is the tunability of these headphones – the nozzles are interchangeable, and there are two bass/sub-bass ports on the housing. It’s surprisingly simple to switch, although I do recommend working on a clean surface – I’ve already nearly lost a few parts during the switching. Switching does require a (fairly) steady hand, but it’s not a big issue – I believe most people won’t have problems. The filter/port/nozzle container (whatever you want to call it) is tiny and the organization isn’t exactly very elegant, but it gets the job done in a compact way. The container’s also pretty portable and fits into the metal case. Overall, I’m surprised at the build quality of this – its tiny form factor and sturdy housing is pretty nice.

Sound Quality

Since there are 36 possible sound tunings I’m not going to talk about all of them. After some experimenting, though, I’ve found a few pairings that I liked a lot. I’ll briefly talk about those, as well as the overall sonic character of these gems.

It’s hard to discuss these without first talking about the tuning. So apparently there are 4 nozzles which influence the mids and the highs, 3 bass tuning filters, and 3 sub-bass tuning filers. I think everyone’s going to stop reading this (and pass up on these things… ) if I discuss all these nozzles in detail, so I’ll just stop obsessing over them now. I did give all of the combinations a try and eventually settled on a few that I found was wonderful for the genres of music I listen to.

Pairing 1: Red (High sub-bass) – Grey (med bass) – Gold (high mids/med treble)

Pairing 2: Red (High sub-bass) – Grey/Black (med bass/high bass) – Black (med mids(?!)/mid treble)

Pairing 3: Black (Med sub-bass) – Grey (med bass) – Green (med mids/high treble)

First Impressions:

Geez, these things are good. Straight out of the box they sounded so smooth and clear at the same time already. The soundstage was spacious, vocals were airy, bass was there but not too much… Compared to the Westone 4s these sound very, very clear. The detail is really nice – I could hear the smallest breath noise from EXID – and vocals seem very natural. Treble seemed slightly brighter than what I’d gotten used to on the Westone 4, but in a good way. It was clearer, a bit more shimmery but not to the point of being sibilant or intolerable. Seems like we’ve got something glorious in the making here….


As I’ve said, I’m pretty sensitive to sibilance. By all accounts this isn’t a pair of super bright headphones, even though with the green or blue nozzle you could make it border on burning your ears out. With the less treble-happy tunings, however, the treble is very clear and effortless – it’s just there. Even when I used the green nozzles, with the right tuning I could tolerate the slight sibilance of the pop tracks. In orchestral music, especially, the treble is bright, but not overly so – just enough that you can maintain an excellent balance between detail and smoothness. Cymbal clashes sound very lively and energetic, with just the right amount of sparkle. It’s a pretty good balance. With the more treble-happy nozzles, there’s more detail (and sibilance), but with the right tuning and right tracks it can make the orchestral pieces sound incredibly detailed. The airiness also makes the treble extremely natural – and this isn’t just limited to the green nozzles, it’s the same for the gold and black nozzles.

Warning: with the wrong tuning using the green nozzles these can be extremely sibilant. You have been warned.


I enjoy the mids immensely on the FLC8S, especially with the gold nozzle. Vocals seem very airy and detailed; the mezzo-soprano’s voice was captured perfectly – it feels like I’m listening to a live opera performance. There’s probably no way to screw the mids up on this thing – they are that good. Nuff said on them.


Ah, the magical red filter.

Orchestral music just comes to life here – the bass isn’t exactly linear like reference flat headphones (Brainwavz B2, looking at you) – slightly more exciting than that. It adds another dimension to the music, there’s the constant presence of the cellos and double basses; yet they don’t overwhelm the piece – they’re just there, like everything else. The sub-bass extends pretty low, with a nice rumble and I don’t really notice any mid-bass hump – probably because I’m using the mid bass ports – and so the bass is very strictly controlled the whole way. It’s also pretty quick – EDM lovers will probably be satisfied with how the bass handle your music. I’m really happy with how these handle the bass region – they’re so in control, so authoritative when I give it my attention, yet unassuming when I need it to be. Probably my favorite part of the whole spectrum.

Across the spectrum and other notes:

These are incredibly coherent – the designer (Forrest Wei) has done a really good job doing the crossover of drivers. It’s hard to characterize them by a single sonic signature, but in general I’d say they are rather balanced, and slightly skewed towards either the cold side (with the green nozzles) or warm side (higher bass). There’s no noticeable hump in any region as far as I’m concerned, and they are rather spacious no matter what you do to them. The soundstage is very wide, with pretty accurate positioning, and there is no veil even if you crank the bass up. They also don’t have that artificial timbre that I sometimes get from other headphones (especially some IEMs with metal housing) – everything sounds very natural, and I noticed that especially with the mids, they just seem so effortlessly smooth yet detailed. It’s a wonderful feeling.

I feel like the difference between the nozzles/ports are very noticeable and they really do a lot to change the sound, but ultimately the whole sound signature is still built on airiness, detail retrieval and great control – and no tuning can change that. Which is a good thing.

My favorite pairings…

Combo 1: Red – Grey – Gold

This is what I use for a lot of vocal-focused songs. I feel like it gives me enough bass rumble and excitement to pump up the piece, yet it doesn’t overpower the vocals. With the gold nozzles, vocals are prominent, smooth and airy – very very realistic, as if I’m watching a live performance. I feel like the “magical red filter” just helps improve everything – bass presence, warmth, balance, etc. Using the black filter kind of takes away from the whole excitement.

Combo 2: Red – Grey/Black – Black

Grey’s a more neutral choice, and black’s a bass cannon (well, not really, but on the scale of FLC8S…)

I usually listen to pop songs with this combo, mainly because it’s the most versatile and balanced across all spectrums. It doesn’t provide any emphasis on any region and everything is smooth across the spectrum – no humps, no peaks – and even pieces that aren’t mastered that well sound fairly musical. Again, the red filter does its magical job again by up-ing the oomph – the thumping when listening to dance pop music is incredible. When I use the black ports instead of the grey ones, the FLC8S instantly becomes a more bass-heavy headphone, akin to the Westones in quantity, but exhibiting more control in my opinion.

And you know what the best part is? It still doesn’t overpower the other parts of the spectrum.

Combo 3: Black – Grey – Green

Pretty bright combo – I thought it wasn’t my thing. I was wrong.

Listen to a vocal piece with this and the green nozzle absolutely nails the high notes. Listen to an orchestral piece (and maybe using the “magical red filter”) and hear the violins come to life, performing right in front of you. Although I’m usually not a fan of bright treble I absolutely love this combo for classical music – somehow the treble manages to be airy, detailed, with slight sibilance but tolerable by my standards. It gives me so much more detail to look for during orchestral pieces – the attack, the cymbals crashing, the balance… I’m amazed at what these little IEMs can pull off. It’s bound to be something a treblehead will enjoy, listening to all the detail in there.


Even though they are really, really easy to drive – already sounds pretty well straight out of G4 and a bit of improvement with the Dragonfly – they scale up pretty well. On my desktop setup, using the O2 enables me to hear even more detail on the same piece, and everything is just tightened up a tad bit more. Not a hugeimprovement, but definitely noticeable.


I think airy and detailed seems to be the common theme between all the different sound signatures here – I feel like the FLC8S are an incredibly versatile pair of IEMs with its foundation built on the two qualities that I cherish most. For me, these are end-game IEMs – it does everything so well that I don’t find myself reaching for other pairs of IEMs in my collection when I’m using these. Everything combined, the FLC8S are an amazing package despite the tiny, tiny problems in terms of design – I couldn’t have asked for more in any pair of IEMs, albeit this pair priced at a mere $250 (or $310). Considering their asking price, I feel like these should receive more attention – even if they only had one sound signature – and everyone should have the opportunity to experience what they pack in such a tiny form factor.


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