For the sake of posterity and the forum search engine...

I had a similar problem when I had to upgrade the amps in my 2 x EP500's and my A1400-8 to an A1500-8 (long story).

I have an aging Denon AVR-4306 which is rated at a paltry 25mA per trigger output which is not enough for the new amps.

I purchased an Emotiva ET-3 "trigger amp" which has three trigger outputs and I'd estimate a total trigger current of about 400-450mA. They cost US$40 plus shipping.

No problems since. The only downside is the ridiculously bright blue LED's so it needs to be hidden behind equipment.