The "simplest" way to operate the home theater is to always use the home theater's speakers (with a good remote like the MX-800 also being a huge help). Any scheme that reverts to the TV's speakers is going to add complexity, although I think that you can probably get it to a manageable situation with the MX-800. Having said that, it sounds like some of the trouble is unrelated to the second zone. The second 12V trigger is operating as intended - it should only come on when you are using an input that has it enabled. It's intended mainly for things like motorized projection screens, and less for amps. The first 12V trigger is on any time that the 990 is on, and that's the one that I'd recommend using for your amps.