I just heard RE-400 at a local meet today. I was blown away by the midrange, bass and soundstage on these things. They are amazingly full, rich, smooth and just plain addicting to listen to. The sound has an inviting warmth and musicality to it. The bass is amazingly deep, tight and punchy. Vocals sounds very clear and lifelike. Imaging is very precise and the soundstage has a great depth to it. The only area where I feel that these could use some improvement is the treble - it's pretty clear and detailed, but I think it lacks some presence in spots - it seems to be a bit uneven sounding and some of the upper frequencies seem to be overpowered somewhat by the lows and mids. Maybe I just got a bad fit though. Despite the treble issues, I still felt that they are a huge step up from RE0 and superior overall to RE262 and RE272. The bass and mids are simply phenomenal on RE400 and remind me of the best dynamic headphones I've ever heard. After switching from RE400 to Ety HF5, the Etys sounded very thin, overly bright, brittle and lifeless - I think RE400 bet them in nearly ever way. ER4 faired better with the midrange quality at least comparable to that of RE400, with more resolution perhaps and more even highs, but the bass and soundstage was definitely lacking compared to RE400.