I too have an ATI 1505 amp that I tried to run off the 950's 12 volt trigger. The main problem is the 950 trigger outputs only 100mA and the 1505 needs at least 350mA to engage the trigger. I currently use a remote controlled universal DC adaptor that I bought at Radio Shack to power the 1505 on and off. It is set to 12v @ 1000mA and works just fine. Not my preferred method but it beats doing it manually.

BTW, if anyone knows how to build an external circuit to amplify the output of the 950 trigger I'd be interested in trying it.