I bought a pair of ad700s a while ago and haven't gotten a sound card for them yet. I'm looking to use them mostly for games such as battlefield 3. Since I'm going to be using them mostly for gaming and care more about the positional accuracy than the actual sound of the game. I'm wondering how much of a difference having one sound card over another can make. I was looking at the xonar DG which comes with dolby headphone. Would there be any difference in positional accuracy (surround sound) in games if I bought a much more expensive sound card with dolby headphone over this one. The xonar DG is 30$ mind you. I'm on a pretty tight budget for the moment. Also which of the digital surround processing technologies is the best? If something other then dolby digital is better could you suggest a sound card under 50$ with that technology?