Thank you so much for the response.
Any idea on what that switching device may be?
I have nothing fancy set up. It's basically just my tv, and I have an Xbox 360, a PS3, and a Mac Mini all connected to the tv via HDMI. I mostly use the ps3 for blue rays, Xbox for Netflix, and Mac Mini or anything that's not available on my other devices. My main concern is being able to produce the sound that comes from the tv AND the airport express through the Bose Wave system (and you're right, it only has one 3.5 input).
Any suggestions are welcomed!