Ran into this issue and designed a box to convert the 12V continuous trigger signal from an Anthem D2 to a pulsed on-off signal that the Proceed Amp 2 and Amp 3 require to turn on off.

I've never run into a device that needed pulsed signals (3-18 V for at least 100ms) to turn on and off. It's such an odd way of doing things.

Anyone else run into this and have a different solution to the problem?