I just installed a Chaintech AV-710 sound card in my living room HTPC so that I can use it's optical connection with my home theater receiver. It is a KOSS KS3102. I have everything hooked up properly, but I cannot get any sound when I use the optical cable. It works fine with a regular RCA cable. I want to use the optical so I will get Dolby 5.1 when watching DVDs on the computer. I made sure that the receiver was set on Optical input. The drivers I am using are from www.viaarena.com since Chaintech's drivers link was broken and everybody seems to recommend the viaarena drivers. The engine on the AV-710 is Envy24. Windows XP SP2. Any ideas? Thank you in advance.