I did see it, actually. (in fact: I think I've seen almost every denon related page

)
Right now, I'm happy to report that
IT'S WORKING !!!
Switching pin 1 and 5 didn't do the trick, but the solution is:
expand the original wiring with a wire on pin 5, leading that to a common ground. For instance the common ground of a wall socket or TV-cable plug.
Marcus, Eric: thank you for your great assistance on this one
