I know there must be cheaper solutions, but the newest line of Panamax's surge surpressors carry 12v triggers to switch outlets specially made for high-current drawing components like amps (i.e. no clamping of the current). I use a Panamax 5300 ($350 online, $500 list) for various reasons -- one of which is its triggering abilities. The model below, the Panamax 5100, has the same non-clamping outlet feature and lists for $350 but can also be had for less.
FWIW,
Todd