I am having a problem, quite opposite to what most of what I've read about Mac audio port issues online, concerning my audio-out port. I'm running an Intel Imac, 7,1, running OS 10.5.8. The specs do specify the audio port on this mac is dual; analog and digital output. Everything I've read to date relates to the red optical light being stuck on coming out of the audio port. My issue is that I CANNOT, and I emphasize that, get the red light to come on and thus use my optical cable (the cable works on other equipment) and connect it to my AV receiver. I have never in the past even thought about using an optical cable so it never was an issue. In fact I never knew the port was dual. The external speaker and headphones work fine and the audio panel in the preference pane reflects that; either says 'internal speakers' or 'headphones' automatically when engaging/disengaging audio phone jack. When I put in my toslink (optical) cable, the panel goes to 'headphones' instead of 'optical out' or 'digital out'. There is never a provision to click on digital out on either the sound panel or the midi setup panel. I've tried everything I can click on at both panels. Audio Output in midi setup says 'master stream' (always greyed out) and Source- either 'headphones' or 'internal speakers'. The default and system output drop downs never give me a 'digital' or 'optical' option. Everything works fine except that I cannot get the red light to shine and cannot get digital out at all. Any ideas? Maybe something in terminal or in openfirmware screen? In short, I cannot get digital output on my Mac.Thanks.