Great choice of headphones-they're great for gaming. (I use a pair of Sennheiser HD 650s) So you took the dive for a pretty good entry level set of audiophile/über high end gaming set of headphones. Wonderful. How about not getting a sound card? The two most important factors (other than the headphone and source) in digital audio are the headphone amp and DAC. (Digital to Analogue Converter) Though many of us audiophiles agree that aftermarket sound cards sound better, a DAC/headphone amp built for headphones like YOURS will make them shine. A great $80 USB DAC/amp will obliterate any $250 sound card with your headphones. The $65 Fiio E10 would sound just as good as your STX, but I believe it has a better DAC, which would improve how it decodes the information. What makes gaming sound cards sound "better" is their digital sound processing, not amp or DAC quality. This software can be downloaded for free or bought for cheap.