Like the subject says - I currently have a Rockboxed Sansa Fuze that I listen to with ER-6is powered by an E5. I'm very satisfied with the isolation from my ER-6is /w flanged tips since I am usually listening to music while commuting on the subway or bus. However, I've been itching to upgrade although I'm not sure where to start. I was planning on upgrading my earbuds first before I get something like the Cowon J3. After a bit of reading, I am considering the Sennheiser IE7s (used probably).
At home I switch out the ER-6is for my Grado SR80s. The E5 is my first amp, so I'm not sure if it would make more sense to upgrade the amp first which might give a bit more push to the SR80s and maybe bring out more bass on the Eties.
My ear's pretty decent, but I'm a bit new to DAP hardware. New DAP? Amp? Earbuds? I would very much appreciate some advice. I'm mostly concerned with isolation (so probably IEMs) and overall sound quality.