The XB500s are actually quite good for dubstep if you can afford to pick up an amplifier with a hardware EQ in it.
Don't get me wrong, they really don't sound too good unless you can spike the treble by a significant amount, but if you can swing an E17 or something of the likes with them they're incredible for dubstep/Dnb. Though I can't say they'd be preferable for a wide range of music by any means.
