If your pre/pro or receiver has a 12vdc output, both Niles and Xantech make switched ac outlets controlled by a 12vdc input. Simply plug your amps into the switched outlets and connect the 12vdc and your pre/pro remote will also activate your amps.
As an alternative, as long as your preamp/receiver has a switched outlet, you can run this to the coil of a 115V relay and have the relay wired to an outlet box ( stand alone) to plug the amps in to.
I have used this setup with a enclosed relay from Radio Shack for years and it works great. Just make sure the relay contacts are rated high enough to handle your amps load ( or use 2 in parallel, 1 for each amp) Good Luck.
See my response above, as long as you have a switched outlet (115v, and most recievers and preamps do), it will work.
You can take an extension cord and cut off the outlet end and connect those wires to the coil of a 115V relay, plug the plug end in to your switched outlet. That will close the contacts of the relay any time the reciever or Preamp is on.
For the contacts part of the relay, you run a cord from the wall outlet to one side of the contacts, and wire a receptacle box to the other; my relay was small enough to fit in the box so I did not have to construct anything to hold it. Then plug your power amps in to the outlet box. Hope this description helps.