Just got my HE-500s. Some impressions (compared to HE-400):
- More forward mids and fuller sound
- Smoother treble. Cymbals sound much better
- Voices are better portrayed. Female voices sound awesome, really.
- HE-400s have more(quantity) and better(quality) bass. But the bass on these is still pretty good.
I'm using the velours by the way. Didn't test it with the pleathers, but it'll probably change for worse, so I won't even bother.
By the way, first thing I noticed is that HE-500's atleast as loud as HE-400 at the same mark on my amp's volume pot(Burson HA-160). Actually I feel it's even louder. It's probably due to the less recessed mids, compared to HE-400. I can go further too without fearing the treble will hurt my ears.
All in all, I'm very satisfied with these. Although I'm not really sure yet if they're worth the $300 plus compared to HE-400, I don't regret buying it. Great headphones, really.
Edited by Okamoto - 7/23/13 at 1:21pm