What is a good sound card that I can use in my PC and link to my 5.1 Sony Home Theater System (DAV-BC150)?

If I am understanding your question you want to send the sound from your pc to your home theater system. You need a special sound card for that. All you need is a simple cable. You can get it at radioshack. It would plug into your audio out on your computer and into the back of your theater system into the aux jack using audio right and left rca cable. Which should be white and red.

You don't need a special sound card for that if all you want is two channel stereo. If you want 5.1, 6.1 or 7.1 surround sound, then you will need a higher end card and a SP/DIF digital connection. You will need a SP/DIF optical cable (best) or electrical cable with a single RCA connector on both ends. It's a single cable that transferes the digital signal. Here's a few really good cards to look at. If you are a real audiofile, stay away from Creative Labs cards. Turtle Beach Catalina - http://www.turtlebeach.com/site/products/soundcards/catalina/ M-Audio Revolution 5.1 - http://www.m-audio.com/products/en_us/Revolution51-main.html M-Audio Revolution 7.1 - http://www.m-audio.com/products/en_us/Revolution71-main.html

Correction to my post small typo. I said you need a special sound card. I meant you don't need a special sound card. Sorry

can you get 5.1 sound out of a 1/4 inch digital output on the card? i soldered a single RCA cable to a spliced stereo 1/4 patch cable and soldered the 1/4 end to mono. all i use it for is Stereo. would it also put out 5.1 or do i need a optical output?

SP/DIF (digital) can be transfered in two ways. One is the optical cable. The other is just a cable with RCA connectors on both ends. Now don't get me wrong. The RCA cable is connected to the digital jack, not the analog audio jack even though they use the same type of connection.