Okay. OP, go spend five minutes looking at the Beyer DT880. Then buy the Sennheisers.
This might be helpful (more seriously):
I roughly agree with his "findings" that the Sennheiser are the best all-rounder for most people; I haven't heard the 880 but I have never heard a Beyer that I've liked, so take that in mind. The K701 *are* very good for what they are, and if you like their sound, they're heavenly until you find something more analytical, faster, or otherwise superior (this is usually in the form of an electrostat or a *very* expensive dynamic). And even with that superior phone, the Sennheisers are still "good" - really they're just unoffensive and can wade into anything and at least do a half-decent job. I still think the $500 price tag is a bit nutty. But the times are a'changin.