I picked up the SE215s yesterday too and am having the same problem. Trimming down the foam on the black sleeve tips helped a little, but not enough. Coming from the Sennheiser HD 25s, the mids (+cymbals like you mentioned) sound harsh and similar to how I'd expect a <128kbps MP3 to sound. Bass is fine at least.   I'll probably try getting some replacement sleeves before giving up entirely.