Ok sorry for the delay, I'll spare you further excuses and just post my interim findings.
I've still had only about 15 hours with the K3003 though, so take this with a grain of salt. As I've said before, there isn't a night and day difference in sound quality between the K3003, FI-BA-SS and UERM overall, but with low volume listening things become more distinct and the K3003 rise above the others. Why is that? Well, on the one hand because their dynamic bass driver delivers the best texture and on the other hand because the AKGs have extremely good dynamics, even when played rather quietly. The FADs need a little more volume to come alive and the UERMs stay rather bland and unenthusiastic until about mid volume.
Low volume listening: K3003 > FI-BA-SS > UERM
Now let's see how these phones compare in detail at normal volume levels:
Speaking of bass texture, the K3003's dynamic bass driver is excellent, fast and extended, there when needed and out-of-the-way when not. There's a little hint of midbass elevation and warmth, enough for those who find phones like the FI-BA-SS and EX1000 too lean, but it's never obtrusive and stays well clear of the mids. Integration with the dual BA mid/treble drivers is seamless and surprisingly coherent, though those familiar with the characteristics of driver technologies will of course be able to tell that both are being used. I'd normally rank the FADs on top, since I prefer a leaner sound signature, but the AKGs are so impressive with drums and upright bass, that they end up on par with the FI-BA-SS. I'm afraid, the UERM have the least impressive bass in my book, still well defined and extended, but slightly lacking in texture.
Bass: FI-BA-SS =
K3003 > UERM
The mids are where the UERM are at home and their midrange is simply marvellous, smooth, detailed and extremely refined. However, it is also noticably forward and you'd have to like the kind of vocal intimacy that goes with it. The K3003's mids are only a little less forward and imo exactly where they should be in relation to bass and highs. Their quality is again excellent and doesn't fall short in the least vs. the UERM, but I mids lovers would probably still prefer the UERM over the AKGs. The FI-BA-SS have the least conspicuous mids and even though they're not recessed or lacking in any way, your attention will inevitably be drawn away from them and towards the highs with these phones. The ranking is very close here, but still I'd say:
Mids: UERM > K3003 > FI-BA-SS
Treble is perhaps the most controversial part of the frequency range, cause there are those who're sensitive to spikes and others who like it lively "up there". I belong to the latter group and love a good amount of lively treble as long as it's not "metallic" like on some BAs or overly sibilant. Therefore the highs on the FI-BA-SS are a dream come true for me, since they bring classical music to life like nothing else I've heard. But the FI-BA-SS sound also highly revealing, raw and at times downright ruthless because of these highs and it goes without saying that they are definitely not for everyone. The K3003 have noticably better behaved highs in comparison, but still extremely impressive clarity, detail and sparkle. Somewhat similar to the PFE232's, these are world-class highs and strike probably the best possible balance between liveliness and forgiveness. The UERM's highs are more restrained in comparison, while retaining the same high level of detail retrieval and overall quality. They'll never offend anyone, but they've also the least ability to breath life into music.
Highs: FI-BA-SS > K3003 > UERM
Detail retrieval is an easy one, 'cause even though these phones have noticably different sound signatures, all three are extremely detailed and well suited for analytical listening.
Detail: FI-BA-SS =
K3003 =
UERM
Of course that doesn't mean that detail is equally apparent among all three phones. On some you have to listen a bit closer for it than on others. The lean FI-BA-SS are the clearest and most revealing IEMs and there isn't any part of the frequency range that appears obscured. The K3003's dynamic bass driver lags only a smidgen behind in clarity and the rest of their spectrum is flawless. On the UERM both bass and treble take a slight back seat compared to the mids and as a result the midrange appears extremely clear and both ends of the spectrum a tad less so.
Clarity: FI-BA-SS > K3003 = UERM
Separation is slightly different from clarity in that it's about what happens to clarity when things get busy. The FI-BA-SS have the best clarity, but their single driver suffers slightly more in comparison when exposed to a wall of sound. The K3003 and UERM both have very good clarity and manage to retain an outstanding level of separation, regardless of what you through at them.
Separation: FI-BA-SS =
K3003 =
UERM
I rarely mention dynamics separately, but the K3003 are just that good at it, that they deserve to win that point. Easily among the best (if not the best) I've heard. At higher volume levels the UERM approach the FAD's level of dynamics, so I rate these two about on par.
Dynamics: K3003 > FI-BA-SS = UERM
Good dynamics is a vital ingredient for soundstaging, as it lends depth and layering to the presentation. Not surprisingly, the K3003 excel at that and there's a stunning, almost holographic quality to their presentation. They don't quite reach the same width and openness as the FI-BA-SS (probably helped by the latter's "balancing air movement" design), but their layering is unparalleled among the IEMs I've heard. The UERM's presentation is somewhat underwhelming, not bad per se, but lacking in comparison.
Soundstage size and layering: K3003 =
FI-BA-SS > UERM
Its rather limited soundstage makes it easier for the UERM to provide spatial cues and as a result their positioning is more exact than the other's, which have to fill a larger space. Both the K3003 and FI-BA-SS still manage a very realistic placement, but not quite as precise as the UERM.
Positioning: UERM > K3003 = FI-BA-SS
Last not least, isolation is one of the undeniable advantages of custom IEMs and sure enough the UERM best both universals in that regard. The K3003 have decent isolation, but probably not enough for commuting a noisy subway. I actually think it's rather low for a closed IEM and I think there might be a hidden vent somewhere. The FI-BA-SS are definitely vented, but (if worn with a deep seal) isolate almost as good as the K3003.
Isolation: UERM > K3003 > FI-BA-SS
(Preliminary) Conclusion:
As you can see, these are rather mixed results, except for low volume listening, where the K3003 really stand out. But if I'd be forced to part with one of them, it would be the UERM, since their only advantage over both universals is isolation and that's not high on my priority list. The other question is, which IEMs would I pick if I could keep only one? I think that would be the K3003, not because they're better than the FI-BA-SS, but because they're more forgiving and work better with a wider range of music. The Final Audios would probably render about 70% of my music collection obsolete, because they just need stellar recordings to sound good. So, to those who want to squeeze a winner out of me at all cost (even my fingernails
, I surrender and give you a name: K3003
