so my setup would be soundcard optical out -> superpro optical in -> amp
is optical better than coaxial?
Dolby.com,who I think would know a little bit about digital audio connections say.
"If your system components allow you to choose between two types of digital connector, note that both have identical audio performance. Under some circumstances, however, very long coaxial cables can be more susceptible to radio frequency (RF) interference than optical cables. Because optical cables are more expensive, try coaxial cables first and switch to optical only if you encounter problems."
So I guess the bottomline is, if it sounds good with coaxial, stick with coaxial. If you get too much interference, have the money to spend, or only have a digital output, then go with optical.