Axiom in looking into the issue and if they come back with it likely being a cable issue then I will have to special order some mono cables from the USA as I have not found any here.
My first thought is stereo vs mono cable as well, although I have to admit that 40mA seems pretty low for a trigger output.
I did find at least one 1/8" mono cable locally though:
https://www.amazon.ca/TNP-3-5mm-Mono-Cable-6FT/dp/B01MEBXOOP/ref=sr_1_13?ie=UTF8&qid=1509908901&sr=8-13&keywords=1%2F8+mono+cable
I need to stick my head into Sayal next week (they often have buckets of things you can't find anywhere else) so will keep my eyes open. Will also look at your relay thread tonight... rain has stopped briefly so need to run out and get back to brush cutting.
BTW apparently trigger incompatibility seems to be a problem since AFAICS there are no industry standards, but the usual workarounds seem to be:
1. If your master unit has a switched outlet plug a 12v wall wart into it and use that to trigger the other equipment
2. If no switched outlet then get a current sensing master/slave power bar (something I did not know existed until just now) and plug the wall wart into a slave outlet.
Dumb question - do the amplifiers on EP500 and ADA1000 generate much heat when idle ? If not I would be inclined to leave them on all the time rather than switching on and off, although the whole "switching on and off is the hardest thing on your equipment" may be an old wives tale, not sure.
I probably should switch my old Adcom off when not using it, since it definitely generates some heat even at idle.
