Quote: Originally Posted by hungrytoheal
. I then plugged a Y adapter from the red and white AUX IN ports on the main unit into the green jack on my sound card
There's your problem. You're dropping down to two channels. Composite [Red/White/Yellow] is not multichannel like HDMI or Optical because it is purely analog and there just isn't enough room for multiple signals.
To get surround sound, you'll need a surround receiver that has at least 5.1 channels of output AND input. You can convert the 3.5mm from your PC's jacks to Composite, as long as you keep the same quantity of channels.