If you find using the digital cuts the analogue (it may or may not) there is an answer for you: Get a digital splitter and a digital to analogue converter. Run one output from the splitter to your surround and the other to the analogue converter and on to your Altec Lansing speakers.
CB
ps I am looking forward to the demo video and shots from this feature of your new kit:
Karaoke Scoring
Karaoke Scoring is an advanced feature that automatically rates your singing and gives you a humorous picture that is tied to your scores.