I agree that the RE272 have better highs, but the mids were just too lean for my liking. The bass I disagree with you though. The bass on the RE272 I found to simply be one of the worst I've ever heard, and that's comparing it to the Ad700 and RE0. It's not bad quality, but the severe lack of quantity made the RE272 horrid for electronic music. The only thing I really dislike about the q-JAYS is the sibilance, but as time goes on it's less and less.
RE272 is very sensitive to fit and tips used. With a good fit and the right tips, they have amazing bass response. Maybe a little lean in the sub bass, they produce a very neutral, accurate, incredibly detailed and dynamic low end. The mid and upper bass are simply stunning on the RE272. May well be the best bass I've ever heard.
Oh, the Q-jays have very solid bass response for sure and I would actually probably rate them in 3rd place among all IEMs I've heard to date. They used to be my IEM bass champs for quite a while, until I heard the ER4, FX700 and RE272. Their bass is excellent really. I wish some other IEMs costing 2+ times more had such nice lows. Detail, speed and definition are great. But while they are really, really nice, they are not quite at the ultimate level of an ER4, FX700 or RE272 I believe. Q-jays are missing some dynamics and are not quite linear down there with the mid bass dominating over the upper and sub bass at times. Their bass just doesn't quite have the character, nor the detail of the aforementioned three other IEMs I heard. It just doesn't go that extra mile to deliver all the goods so to speak, stopping just short of the goal.
BTW, out of good sources, the bass on Q-jays gets even better. I tried them out of my AMP3 when I had it, which is a really nice source for a DAP and the combo sounded superb in the lows and mids. Really, Q-jays probably beat or at least match about 90% of all headphones I heard in the bass department, regardless of type.
Edited by Pianist - 10/4/11 at 6:54pm