ASUS Xonar D2X and Gaming
I'm going to be buying a new PC that comes with a 7.1 Headset. My motherboard supports it, but I'm not sure if the ASUS Xonar D2X would be the right match, since I'm using the PC for gaming.
I used my onboard sound for quite awhile with my 7.1 Razer Tiamat and had no problems whatsoever. I switched to a Creative 7.1 sound card because I got it on sale for pretty cheap and wanted to see if it would make a difference. While there was somewhat of an improved audio experience, I wouldn't have called it noticeably greater. Granted, it's not an ASUS Xonar so I'm not sure how it stacks up in comparison, but I guess my point here is your onboard sound should be good enough for gaming with a headset, if you're familiar with installing sound cards yourself, I'd recommend trying it out first with the onboard and adding the ASUS Xonar afterwards if you're not satisfied.