I've got he SupremeFX X-Fi sound card http://www.asus.dk/Motherboards/Intel_Socket_1366/Rampage_II_Extreme/
So it's somewhat pretty crappy. And sometimes the sound meshes up :S. So maybe gonna get a sound card some day anyways :P
I have looked alittle on the Q701, but i just thinks it's alittle to expensive, if i need and Mixamp or sound card to.
I'm Probaly a Mixamp, but can't decide that either, which one to grab, to which Cans.
The prices in Denmark is somewhat more expensive than US.
The Q701 goes for 250£ and the 770 80 ohm and 990 goes for 120-140£, the HD598 is 160£.
It's pretty hard to choose which combination of setup will suit best :P
Hope the information is good enough :p