Optimizing Your Setup
When it comes to plugging analog audio from a sound card into a sound system, you've got two basic options. You can try your luck with an auxiliary input and see if voltage levels are sufficiently compatible to make that work (I had no problems with the Sony, Kenwood, and Yamaha equipment I tested this approach on), or you can use the old "tape monitor" trick. In this approach, you route the pre-amp or receiver's tape output ports to the sound card's line-in port, and then route the sound card's line-out port to the receiver's tape input port. By playing back sound on the receiver and toggling the tape monitor button on or off, you can adjust your sound card's level set to deliver the same level of signal strength on the tape input port that's going out through the tape output port. This is a rude and crude but effective way to match up sound levels so that the volume control on your pre-amp or receiver controls sound levels on its speakers efficiently and effectively.
When it comes to managing sound levels through optical, coax, or S-Video connections, some fiddling around is required to get sound levels to match up so that neither the sound card nor the sound system has to work too hard to play things back at a listenable level (thereby decreasing chances of noise or distortion). Of course, keeping cables as short as possible and using the highest-quality cables and connectors available greatly improve the sound quality and the listening experience your hook-up delivers.
Therefore, if you needed another argument to move a Media Center PC into your living room, you just got it. Enjoy the resulting sound, viewing, and gaming experiences that result!