In my experiance, the M1 I had did not have enough current to run a relay or the amp's remote turn on. While I had that problem I tested that wire while connected between the power supply and the amp and the voltage dropped a significant amout to not allow the amp to turn on or a relay to be energized.
Why dont you just wire up the remote line of the radio to go to the power supply and the amp. If you are worried about current you can use a relay. There is no sense of dasiy chaining all of your turn on wires to turn on in sequence. Unless you are worried about turn-on pop you can go with a timed delay relay.