
Sennheiser HD-595's and a Beresford TC-7510 DAC + Headphone Amp, connectioned to my X-fi via optical. Absolutely blows away my Medusa 5.1's for musical clarity, and using my X-Fi CMSS-3D tech, positional sound is much more convincing too - just scared the crap out of myself in Bioshock - 7.1 with vertical positioning ftw! (Cost me £200, but I see it as an investment vs Spys for the sniper update

)
The Sennheisers are awesomely comfortable too, I've got a fairly small head, and this is the first set of headphones that really sits right (and there's even adjustment room to make them smaller! ) My Medusas always kinda felt like the earcups were hanging too low, even on smallest setting.
The 595's weigh next about half as much too.