Recommendations?

I use my computer for everything these days (gaming/music/film/anime, etc), so audio fidelity is important. I have a leftover Xonar DG 5.1 from a previous build, however my mobo barely has a PCI-E 16x open, and I would rather not block the fans to my GPU. So I need a good 4x card. I've looked at the Xonar DGX and DSX, but before I put down money on either card I want to know if one is superior to the other or if there is another in that price range that offers better performance.

Output device: JVC HA-RX700 (considering getting a good receiver and surround setup down the road).