Depending on your video card, your best audio output is via HDMI from your video card into your Receiver. Most newer video cards will output the best stream they detect and can decode via HDMI. Your receiver accepts Dolby True HD, and DTS Master audio from BD discs, as well as 7 channel uncompressed PCM via HDMI.
If you are a total fantatic about your 2 channel stereo setup, you could migrate to an M-Audio, or Asus Xonar card.
So no point then I'm assuming? I have a GTX 480 and will soon be upgrading to a GTX670. Music (and thus stereo sound) is a low priority for me, I'm more bothered about movies sounding as best they can.