I think the audio delay is something you use to match up the dialog to the television set. Some TV's have a slower reaction than your receiver, so it looks like the old Kung Fu movies... the words are a couple of fractions of a second behind or ahead of the speaker's mouth and it can be really distracting, especially if you just dished out three or four grand for the new video. You can set the audio delay to match the motion to the words.
Since the receiver has no way of telling what kind of delay your TV needs, I think it's strictly a manual setting.
