Dude, if you game on PC, don't use the Mixamp. AT cheapest, get a Xonar U3. If you have an optical dac (cheapest being a Fiio D03k), you can completely bypass the Xonar's amp and dac, and just send the Dolby Headphone signal to your own amp/dac. I have one, and I send the signal to my Fiio E17 amp/dac (which has an optical input). Sounds great, and the U3 is hella cheap.
It's not worth spending more on a better pc device, since you only need it to send the signal to your own amp/dac. U3 is a perfect choice.
I really need to add it to my guide.
I came across the Asus Xonar U3 while researching alternatives for laptop use. Shortly after that I acquired the Asus Xonar U7.
I like both and would have zero qualms about recommending either (depending on scenario of course). I primarily use the U7 on my laptop paired with AKG K712 Pro.
And yes, you definitely should add the U3 to your guide .... and the U7 while you're at it. It would have saved me (and it's all about me right? right?! ;->) so much time when I was researching headphones and surround sound processors for laptop use!
Since we're all talking about itches ...
While I'm thoroughly enjoying laptop -> U7 -> K712 for the past couple of months, I find myself reading about Project Ember (oooohhhh shiny). And wondering what a good DAC pairing would be???? Then I have to remind myself one step at a time.
Which leads me right back to thinking on Laptop -> U7 -> DAC -> Project Ember -> K712 .... and somewhere in there I have to try a good pair of closed headphones to complement my open ones (believe Change recommended the Shure 1540). And now my portable solution is lackluster AND vmoda released the XS .... sigh