Yes, I know there are three states. But I only care about two. In standby or not in standby.

Actually, the following logic table(s) would work:

State - Output to power wireless bridge.
Off - Off
On - On
Standby - On

Even the table below would work:
State - Output to power wireless bridge.
Off - Off
On - Off
Standby - On

Again, I just want the wireless bridge power supply to shut off when the empeg shuts off to save the battery.

wfaulk: What do you mean by power line? The ignition? If so, ignition line is off when unit is in standby.

I don't see how looking at the amp line and the power (memory?) line would do what I want.

I hope this clears things up.

-Ed