I would like to use the 12 volt lamp output on the back of the GLD-80 to power the relay that turns on the amplifiers about 100 feet away from the console. The amp relay draws very little power (less than any lamp) and conceptually it would work fine but my concern is how hardened is the 12 volt source.
By connecting that source to a 100 foot wire one opens the door for induced spikes from nearby lightning and also the possibility of a short circuit due to error.
Does anyone know how that voltage source is generated and is it current limited or otherwise protected? What sort of damage could be reasonably inflicted by using that output for something other than a lamp?
Interesting use of the lamp voltage. Just use shielded mic wiring and you should be fine from a stability point of view. Your amplifiers will turn on after the mixer powers up, but unfortunately they will power down after the mixer, which is the wrong sequence. Maybe you have a plan for that. I used two sequencing power bars, one at the amps and one at the desk to ensure everything cycles in the correct order at the press of a button. In fact I have two power buttons in different areas for convenience.