I can confirm thst it's the aux socket, and AUX is displayed on the panel. There isn't a powerlink socket, only a masterlink one which is of course impossible to confuse.
I have also rewired the DIN plug to a mirror image as it has been suggested that pin numbers can mean different things to different people.
Both versions are silent, both with the iPod volume at max and the ouverture ditto.
I am stumped, but continue to believe that it's most probably me doing something stupid!