There's also the possibility that the karaoke player either disables the multichannel out if the digital coax is being used, or is also not set up properly to use the multichannel outs.
In your AVR manual, page 23 describes how to listen to the multichannel input. It's very straightforward. If you play music on your PC, do you hear it through the left/right speakers?
In your AVR manual, page 23 describes how to listen to the multichannel input. It's very straightforward. If you play music on your PC, do you hear it through the left/right speakers?