Rubbersoul, you're right about the remote turn-on by pressing an input button. That way it just takes one press to both turn on the 990 and select an input. Of course the problem for new owners is that it's different from previous experience.
Re the 12v turn-on signal, if your amp is an Outlaw it must be sensitive enough for the 990's 50ma signal to turn it on (some terminal strips, e.g. Monster Cable, need 100ma as I learned the hard way). Either your cable is defective or your 990 isn't putting out a trigger voltage. A cheap multimeter could immediately tell you which is true. I'm sorry to say that for me it was the latter, and my first 990 had to be replaced. Hope you're luckier.