Okay, I have an Apple TV 3 and a 2011 11" MBA running Mountain Lion. I can get AirPlay Mirroring up and running with no issues between my ATV3 and MBA. But audio is another story. I've gotten it to work at times, but it's never really an easy journey. The problem I'm finding is that when I go to adjust my Sound settings on my MBA (Output to Apple TV) something strange happens. Most of the time, selecting said option will immediately put the Apple TV to sleep and my MBA will automatically revert to the default output Sound setting. One slight workaround was to adjust the Sound settings to Output - Apple TV before turning on my Apple TV and connecting via AirPlay Mirror. Even then at times it doesn't work for me. What is going on? Why am I having so much trouble to get audio to sync with my MBA and AppleTV? Why does it do this strange immediate sleep of the ATV when I try this? Please help. Thanks.