That's pretty much the issue: they don't give a full sound and are not warm. In the review over at anythingbutipod, they had this to say about them:
"A personal anecdote: the Audéo almost appear to be specially made for listening to the band Opeth – they handle both their airy acoustic interludes and their brute metal parts equally well. I can’t say the same about too many other earphones."
That's not a quite accurate assessment. Acoustic parts sound fine, and yes, they can "handle" the heavier parts too, but that doesn't mean they sound especially good doing so. I'm also confused about people saying that either I'm not used to their particular sound yet, or I'm simply not used to IEM in general. I already stated that I have very little experience with IEMs, but I don't understand how that has anything to do with my hearing. Getting used to the specific "coloring" of an IEM or headphones isn't really reassuring. I thought the true test of an output device was them outputting as close to the source material in the way it was recorded gets, not how many different ways they can change it.
To put it bluntly, most everything sounds flat and synthetic. If you've ever heard Fear Factory's Demanufacture, that's the kind of sound (90's "cold" production) I'm getting for pretty much everything with the grey filters. The highs are muted, and turning them up with the EQ makes the other frequencies sound "hollow". Getting used to these isn't going to change that.