If your preamp has a switched 115 volt outlet just go to Radio Shack and buy a 12 volt wall power supply and use it to turn on the amps that have trigger inputs.
If the power anp does not have a trigger you will need to use a relay to turn its power on and off. This relay can have a 12 volt or 115 volt coil, depending on what your preamp can supply. Radio Shack for relays. Install the relay in a large electrical box, with outlets according to your need.
If the power anp does not have a trigger you will need to use a relay to turn its power on and off. This relay can have a 12 volt or 115 volt coil, depending on what your preamp can supply. Radio Shack for relays. Install the relay in a large electrical box, with outlets according to your need.