ze kink
THE BLACK WIZARDS
I'd love to try the Denons but I literally don't think I'd be able to feed them from anything. That's the biggest hurdle there.
I've not got great feelings about these Beyers. They're sounding really hollow and weird. I think I should've had more conviction in my own conclusions during testing, and not have bought into some graphs that mean nothing.
Remember, it's not all about the resistance. Headphones with a low resistance will need more current, and that'll distort headphone amps with poorer quality rather easily, since they haven't got enough juice to drive them. I do believe that the 2Control should handle that, though.
Headphones (and monitors, really) are just such a taste thing that you really need to try before buying. Unless you've got the blank canvas mentality and just learn to use everything you get your hands on, which is pretty much what I consistently do, if something impresses me but I've no chance of trying it myself. If you're looking for a specific sound, it's definitely very very difficult to find what you're looking for with just shots in the dark, pretty much.
I'd still suggest that your best bets are the HD-600 and the Denon's, and I actually think that you might prefer the HD-600's even though you hated the HD-650's. The build quality is the same plastic-y thing you'll love and the cable's apparently of lower quality though.
Isn't there a place that would send you a couple pairs of cans for testing for yourself, and then return all the ones that didn't impress you? I'd definitely go with that if it's in any way possible.