> My audio preamplifier/processor is a multichannel fully loaded with RCA,
> Optical and Digital Coax inputs. Now I'm a little confused on what and how
> to connect them.
I would recommend you getting a decent quality coaxial cable with phono
jacks in each end (males), doesn't have to be a top of the line model for
$50+ or anything. Just an OK cable that is sufficiently long to cover the
distance. If it's very far, like more than 4 meters perhaps, a cable of the
better variety might be adviseable. Then you get a phono to mono headphone
3.5mm conversion plug. Stick the plug in the back of your soundcard (digital
output of course

), and the other end in your surround processor.
Do note, you'll only get stereo sound this way, not multichannel...