I have a problem with my MacBook Pro (10.5.8) - the audio output has no sound when connected to a stereo component, but when connected to small speakers it works fine. Internal speakers are working also. Does anyone have an idea?
You seem to have isolated the issue to the stereo component. If it expects line in signal, you might need a device like the Griffin iMic to provide line level sound.
Also, setting the volume lower might make the input low enough to not trip a protection on the stereo, but usually line level is higher than speaker/headphone level so that might not help at all.