I'm looking for a pair of sub-$600 IEMs that are going to bring the best out from well-produced metalcore/melodic hardcore/post-hardcore/technical death metal/pop punk & other genres with a distinct focus & emphasis on the melodic & technical aspects of the guitar work in particular.
The short of it is - I want control & composure as a bit of finesse is important to me - but ultimately a fairly expansive & lush sound with plenty of articulate detail & dynamic impact that's going to enhance my overall listening experience & allow me to immerse myself in the music & it's inherent intricacies.
Being a guitarist myself, my main focus is on the guitars & particularly their tone & note definition, as well as the aggression, drive & impact of the drums. Vocals, both harsh & clean, are also important to me & should have plenty of prescence; but never at the obtuse expense of the guitars' coherence. I guess I'm ideally looking for a pair of IEMs that possess a certain poise & balance to provide an accurate, appealing, organic soundscape full of virility & texture with a sense of depth & intensity - but without sacrificing the clarity & instrument separation that is so vital to the kind of music that I listen to & my own personal tastes.
Low-end: Not really a basshead in terms of sheer power & quantity, but needs to be relatively deep - & as responsive, tight & punchy as possible, the kind that really hits you - but without any noticeable flubbiness/boominess.
Mids: I would prefer them to be slightly more prominent, certainly not significantly scooped, & rich in detail - but simultaneously quite smooth, natural & unobtrusive with good balance between upper/lower ends of the spectrum. No abrasive grainy 'ice pick' kind of phenomenons - but at the same time I don't want them to be veiled or muddy.
Highs: I do like my treble, so ideally it should be quite extended in range with plenty of sparkle & clarity to provide a bit of a distinctive edge to guitars & clean vocals & a nice shimmer to cymbals - somewhat bright, but short of entering sibilance-inducing territory.
Hope you don't mind my jumping in here. Reading your explanation of what you're looking for I would recommend you give the Earsonics SM64 serious consideration. Joker rated them highly and you can read the various comments I've made by doing a search on my user name.