Hooking up PC to Home Theater

Can I get 5.1 surround sound from pc to stereo receiver through optical audio out? I've tried but it seems I can only get sound through hdmi. I get no sound when I select "S/P DIF" as default playback.

Are you using Windows 7? If so, go to Control Panel -> Sound. On the "Playback" tab, select the S/PDIF output option and press "Set Default". See if that works.

As for 5.1 Surround sound, only DTS and AC3 audio will output to 5.1 automatically. For any other 5.1 source (such as AAC), you're going to need software that transcodes to AC3 on the fly (such as FFDshow or XBMC).

Quote from kakomu : Are you using Windows 7? If so, go to Control Panel -> Sound. On the "Playback" tab, select the S/PDIF output option and press "Set Default". See if that works. As for 5.1 Surround sound, only DTS and AC3 audio will output to 5.1 automatically. For any other 5.1 source (such as AAC), you're going to need software that transcodes to AC3 on the fly (such as FFDshow or XBMC).

setting it as default does nothing. I've played around with the FFDShow audio decoder, still nothing. Do I need to be using the hdmi port on the motherboard to get it to work? I'm currently using the hdmi port on a video card I installed & running the optical cable from the mobo.

No, optical is fine for 5.1. My HTPC uses HDMI for video (GPU) and optical for audio (PCI sound card). You have something wrong in your settings.

Make sure the SPDIF sound device is the correct one -- there can be multiple -- and that the optical out is indeed SPDIF capable (the two aren't synonymous). In W7 sound settings, there's a tab for testing the sound where it will play a chime. It will also let you test what formats (DD, DTS at various sampling rates) the receiver is capable of. Make sure you find one that works. If you can get a test sound, the problem lies within your software.

I am running the same setup as you. I have my HTPC hooked up to my tv via HDMI w/ sound for OTA tv. But for watching movies I use SPDIF coaxial out to my surround sound receiver via this module [ebay.com]. I can easily switch between the different audio devices. In your case can you tell us how you are connecting the SPDIF to the receiver? Whats the make model of you motherboard? Have you tried drivers from your MB manufacturer's website? Windows 7 can't install all the drivers..