I just sent my ASG-2's for repair, so now I have returned to my ER4S after 2 months, and as much as I'd hate to admit, I have I have to say that they're really, really good sounding IEMS - they do separation as well, if not better, than my ASG-2's, which costs nearly twice as much. The ER4S' bass is cleaner and faster than the ASG-2's and I think it does female vocals really well too (the ASG-2 is also as good, sounding more natural). I had many goosebumps during my half hour listening session with the ER4S. I'm glad I didn't sell my ER4S after getting my ASG-2.
PS. I was using luisdent's flat EQ settings.