For the first issue, I'd suggest turning off "auto poll" on that input - see if that eliminates some of the confusion. In theory, the unit should take a moment (maybe a second or two) to acquire the new signal when changing formats (DD 2.0 to DD 5.1 to PCM), and during that process the unit should simply mute itself. I'm not sure about the other problem - it's not something I've heard about.