I listen to mostly prog rock and prog metal, stuff like Opeth, older Dream Theater, Haken, Threshold, To-mera, Epica, Oddland, Andromeda, Rush, Riverside, and so on. For this music at home I am currently using a Q701 with an E17 (with +2db bass boost) and my laptop via USB as the source. For portable I use an iPhone 4 (32GB) with the Vsonic GR01 with no EQ. I prefer a neutral, detailed, and fast sound signature with this kind of music. I actually use these same two setups for all my music, which also consists of various electronic music like ambient, downtempo, and even some dubstep from time to time. Sometimes with electronic when I use the Q701 I use the +4db bass boost on the E17 to make it a little more fun. This is the rock/metal headphone thread, though I just thought I should mention how versatile I consider these two fairly neutral phones to be.
I know most people seem to think the Q701 isn't well suited for rock and metal, but I highly disagree with that. There is nothing wrong with neutrality, detail, and a proper decay when listening to a well recorded rock or metal album. With the Q701 the bass is present, not overwhelming, but is very textured, but still punchy, and can still dig deep when the song calls for it. I personally think a slow overwhelming bass is a big no-no for rock and metal, all it does is get in the way. I'd describe the mid-range as rich, detailed, and smooth with just a touch of warmth. Vocals are up-front and crystal clear, as are electric guitars. I've actually never heard a headphone portray guitars like the Q701 does, not sure the best way to describe it though. I used to focus on drums when I listened to rock or metal, now guitars and vocals stand out more to me with the Q701, and to me it is quite an experience. I find the treble to of course be detailed and bright, but I also find the treble to be smooth, not harsh or sibilant. I'd use the term bright, but not harsh, they are also well extended up top. Cymbals are sparkly like they should be and there is plenty of air and space. Soundstage is of course big and wide like everybody says, I never think it's un-naturally wide though. Things still sound well placed, but I've never been a huge stickler when it comes to soundstage of headphones. It's not small or bothersome, so I can't complain.
The Q701 is of course revealing of bad recordings, low bit-rate files, and bad sources in general, which may be a problem. They don't hide much, which I think is a good thing, some don't think so.
ROCK ON EVERYBODY!!! Happy new year!