Hello,
I just go an Arc and have connected to a Sony Bravia XBR-65x930D TV, to which my Apple TV is also hooked up. Audio from both the TV and Apple TV plays on the Arc. When I connect PS3 (with/without being powered on) to the TV with a HDMI cable, however, audio plays on Bravia speakers, instead of Arc, and reverts to Arc when the same HDMI cable is disconnected from the TV.
Need help resolving the issue. If not, I may have to return the Arc and a couple of Sonos One speakers.