Amplifier trigger from Squeezebox Radio

I have successfully used PowerSwitchII plugin to control an amplifier from an SB3.

I was hoping to do something similar for an SBR setup.

I noticed a 3.3V output from the SBR battery connector (http://cms.diodenring.de/en/electron...eezebox#pinout), but measurements suggest that this is always available when the SBR is powered on.

Does anyone know if this signal can be controlled from the SBR software (using something like PowerSwitchII) ?

Any other suggestions ?