I've been looking to replace my Shure 420 iems for a while now, but the situation has become untenable. I love these phones, at least I love them the way that you love your first real high end anythings. I'm a big jazz fan, and I spend most of my listening time with straight-ahead instrumental jazz (big saxophones, trumpet, trombone) with some classic rock mixed in. I'm interested in highly resolved, rich mids above all else. I wouldn't mind a bit more impactful base than I get from my Shure 420s, but I'm not a basshead.
I've loved my Shures and would gladly buy a new set, but even the 425 is now due in for an upgrade any month now. I have some slight reservations about smaller companies like Heir and Aurisonics, but they seem to have some interesting, innovative options. Does anyone have some experience with these models in a jazz context?
In addition to sonic considerations, i'm very concerned with prolonged-use comfort and durability.