It looks like your soundcard has RCA outputs, so you can do this. Might not be the best idea though. For a short time I ran an external DAC from my computer directly into my amps. It worked, but there are a few things you need to be aware of. You will want to go into your sound settings and mute/adjust the volume on many of the windows sounds. I think you can disable one of the kernals in the newer versions of windows as well (forgot which one, since I have basic computer skills but definately don't know all). The issue I ran into initially was the startup sounds were incredibly loud. I also worried that someone who didn't know my setup would accidently crank the volume in the media player I was using and damage my speakers (sometimes the scroll wheel on the mouse will adjust the volume in Winamp). I went back to using a pream (or AVR) for the piece of mind and better volume control.
