Claude, I will email you, but wanted to answer here, too. Sears has a Craftsman device in the tool dept. that is used for turning on a centralized shop vac system when a power tool is switched on. It has two receptacles for switched devices, and one for the controlling load.

I use mine for switching on my two Sunfire amps, a Stereo and a Cinema Grand, exactly the way you want to use yours. However, my preamp alone does not draw enough current to trip the device, so I use the 12V. trigger out to trip a power strip which I added a 12V. relay to, so my switched components and sub amps are switched. They add enough draw!

Larry
www.fineelectricco.com