I think you are confusing analog stereo audio and composite video. What you refer to as "composite audio" is simply analog audio (left and right channels, typically red and white jacks). Composite is the name for a video connection, and is typically a yellow jack. The two can be used independently of each other. In the setup you described, the DVD player's composite video output is currently unused. You can run component and optical to the TV and composite video and stereo analog audio to the switch box.