Per the last post, I just received my Beyerdynamic DT880 Premium 250 Ohm headphones.
I won't take a strong stance on these headphones until they are past burn-in a couple hundred hours down the line.
At present, through my amp (Maverick TubeMagic D1 with upgraded opamps and tubes), they have relatively subdued bass, perfectly natural and even mids, and "sparkling" trebel. There is no mid bleed, the phones just sound utterly fantastic when playing anything in that mid range. I am listening to Bach's cello suite through my desktop setup right now, which really milks the butter zone of these headphones. The only shortfall might be imaging. There is plenty of air space around the instruments, but it is hard to tell precisely where they are. That could just be a problem with my recording.
Plugging the phones into my phone (iphone 5), I am playing music at 4 clicks down from maximum, that's comfoirtable for listening, maximum is decently loud.. Switching to some Mastodon, I am putting the phones to maximum, and that is definitely loud, although I could see a serious metal fan wanting a little bit more volume to produce the concert experience, but for that she should just get a nice amp!
Techno, electronica, and dubstep all play really well on these phones, probably about as well as they can out of anything.
The two shortfalls of this headphone so far are a lack precise 3d imaging and the sparkle in treble. When a violinist plays a scale up to the top of its range, with perfectly even volume, these phones will play some notes louder and others softer. It's not much louder or softer, just barely noticable for me, but there you go. I'll probably do some EQ to even things out on my desktop setup.
A feature that some might consider shortfall is the relative lack of base. I think a truly neutral headphone would have somewhat more bass at the low end, and sometimes when there are two simultaneous rhythms in super low bass and mid bass, the low bass isn't quite loud enough compared with with the mid-bass.
Wow, listening to Ghosts N' Stuff Nero Remix through these is Amazing, the mid and trebel centered sound has so much texture that I hadn't heard before, but it's an example of a song in which someone else might want more bottom end.
For the price, I think these phones are a really really good buy, and a great listening experience.
Thanks to CrocCap and pp312 for some good advice.