Hi JackBauer, your situation is very similar to mine but what's even more strange is that the issue happens in a different context. All my 4 channels on the Aquaero 6XT are doing fine, and I also have a D5 from AC hooked to it (via aquabus though) and it's ok too.
I feel something just goes wrong during power on, actually behaving like a start boost would do. In your Aquaero ch1 pumps and on my PA3 ch5 fans. Hope someone can explain this