I'm on a (so-far fruitless) quest for a high quality in-ear headphone. It really is a quest. So far I've tried four different models (including two copies of one model), but haven't found a particularly good set.

I'm trying to replace my old set of Sony Fontopia MDR-EX71SL headphones. When I purchased my original set, I was surprised by the even, good quality sound. The only reason I'm replacing them is that I've entirely worn them out.

My first instinct was to replace them with another pair of the same model. Unfortunately, I've bought two replacement pairs and both have much, much worse sound than the original set. Terrible, harsh mid-highs and steep bass dropoff.

My last purchase was a pair of Yahba Opus "extended bass response" headphones. What crap. Don't even bother. Total junk sound.

My benchmark is the set of Sennheiser 590s that sits on my head all day long. If I could get 75% of their quality, I'd be entirely happy.

I think I'm going to break down and get a set of Etymotic ER-6is. I'd love to get a set of ER-4s, but I don't think an iPod can really drive them.

Any other suggestions for in-ear phones?