\rHI Joe:
The 12 Volt trigger input needs to be hardwired (or physically connected) to a component like a Receiver that would feature a 12 volt trigger output so it would send a turn on or turn off signal to the AMP300. The output 12 volt trigger on the AMP300 allows you to send a turn on or turn off signal to a second AMP300 as an example. So the 12 Volt trigger has to be wired to a component that features a 12 volt trigger output. The signal sensing or auto sensing triggers the amplifier to turn on when it senses a signal on the input side from the source (the Amplifier must have the manual switch in the on position for this to work). When it fails to see a signal after 10 to 15 minutes it goes into stand-By mode waiting for the signal to return. So check the Source or Receiver you want to connect for a 12 volt trigger output or you may have to settle for the signal sensing to do the trick.
Good Luck
TL/3729\r