*Updated troubleshooting*  

Hello:   I just bought a pair of KRK Rokit 6's to replace my old Logitech x540 setup. I'm very happy with the monitors, but my problem is they're picking up a lot of interference from my PC, and I need to resolve this issue in order to not go insane from the noise. This is not just the...

Will any of that effect the sound quality?  

I'm looking into getting some new speakers, but am curious as to how they will hook up to my soundcard (ASUS Xonar DX). The outputs are: Headphone / Front; Side Surround; Center / Subwoofer; Rear / Back Surround / SPDIF. How, for instance, would I hook up something like Rokit's with their RCA /...