I have read on here that when you get the headphones, you cannot exit thru SC over to SP but have to take your headphones all the way around to front entrance. What I want to know is can you then go back the way you came and exit out the SC door anyway after turning in your headphones? Or is it a one-way only path? Also, have any of you gone to SP first, early in the AM, and then entered the museum later? (Assuming, of course, that you have your timed entry ticket, etc.)
If you mean headphones as part of the guided Vatican tour, when we did that the guide collected the headphones before we entered the Sistine chapel (she did not go into the chapel with us). So we were able to exit directly to SP. Sorry I don't know the answer if you are just using an audio tour. My family did go to SP first (summer of 2007). I think we got there about 8 AM, climbed to the top, and saw the inside before our 10:00 AM tour of the museum. Very uncrowded that early. After our tour, we did go back to SP, and toured the crypt and went back inside for a last (at least for a while!)look. We left Vatican area about 2:00 as I recall.
And if you mean the audio guide that you rent, that is correct, you need to return them near the museum entrance/exit to get your id back.