[octanitrocubane]

I am considering upgrading my stationary rig from my current setup (Razer Megalodon), since now that I have upgraded my mobile rig I do not want a lesser sounding stationary rig. Sadly I do not have room for a internal sound card,therefore I have decided upon getting the ASUS Xonar U7 USB sound card, as I want to be able to simulate 7.1 surround whilst gaming, but I am open to suggestions here as well. However I have no clue what headphones I should get to match. I recently purchased the Sennheiser Momentum, which are great whilst I'm on my way to/from school or  traveling, but I have found them a bit less comfortable than my Megalodons when using them for several hours in a row, which I why I am considering getting a separate pair for the new rig.
 
Whilst I know that most people recommend headsets with less bass for gaming, I personally prefer something with a bit more base. The most important factor for me is comfort, as I wear my Megalodons for at least 5 hours a day usually. I have not yet decided on the  budget yet, but I think it's going to end up around $300 (including the sound card).
 
Thank you for suggestions/tips!