Hi Jay,
As long as you’re following the original diagram you should be just fine because the Power Station is at speaker level and doesn’t touch the FX loop of the 5150. Can you by any chance send me some clear pictures of the set up? Everything should be happening in the 5150 and the Syn-1. There shouldn’t be anything but the speaker cable going to the Power Station. The other thing to be aware of is ground loops. Makes sure all of this is going into the same power.
Thanks,
Terry