Can I stop the optical audio out from entering 'time out' when idle?
Playing a one-second silent sound every 50 seconds or so might help. Try this:


download 1 second silent .wav file here to desktop (or make your own)
in Terminal, change Directory to Desktop: cd ~/Desktop/ 
Try the following one-line command and see if your problem is alleviated:

while true; do afplay silence-1sec.wav ; sleep 50; done



The command above enters an infinite loop which plays the empty sound every 50 seconds. This should keep your output busy. You can exit the loop by pressing &#x2318;+.

NB: afplayis frequently overlooked for terminal sound playback, but is hugely useful.

If that works, one could convert the command to a command that invisibly runs in the background.