Audio signal sensing auto on/off switch

I've never seen  a source with a trigger in that price range. And who would want a one source system?

@fuzztone 

I meant the source to provide audio signal to the subwoofer amp(s), it can be a integrated amp, receiver or pre/pro.

Is that 12V linked to 'power on/off' of the receiver?

@kraftwerkturbo 

The 12V trigger output will be OFF if the receiver @ standby, it will turn on went the receiver power up.

BTW, if you choose not to diy, the relay controlled outlet box that I suggested on the first post can be controlled by Universal control voltage 3-60VDC or 12-120VAC, or connect directly to a 12VDC trigger, or even 120VAC.

Good idea (to use the existing 'load sensing' power strip to control a heavy duty power relay (assuming that the big amp will melt the strip/contacts). 

Sure this box can use 12DV trigger, not just a digital input? 

Sure this box can use 12DV trigger, not just a digital input?

Yes, I can confirm that this box can be controlled with 12VDC. I have one, what you need to do is connect the green plug to the 12V trigger output.