Xonar DSX has a tiny bit better signal to noise ratio (107dB compared to 106dB for the Rx) and it's customizable with a swappable op amp socket. However personally I'd still go for the Audigy Rx as it has lots more features. It has 3 analog inputs a dedicated digital out and a headphone amp along with the EAX features for games like Quake 4, Unreal 2 and Doom 3.