My drummer has used these as monitors for gigging, and they have been used by our sound guy whilst working the desk, and both have said that the quality these headphones give far outstrips the price.
The sound is very good across the range and gives a decent transparent sound, great for mixing a live gig, or even a recording. They are also (according to my drummer ;-) ) quite loud, and comfortable to ware during a gig, although they never lasted a whole set because, as gigging musos know, it get's very warm and the last thing you want is over ear headphones to sweat into! Regardless, they have proven a very good substitute to a full active monitor.
My only gripe would be that they feel, and possibly look, a little cheap and plasticy, but then, for the money, that is to be expected.
A very good set of headphones, and well worth the price.