Thanks Carl

I had looked at the diagram you refer to but couldn't square it with the comms pin outs in Duncan's info, which for the master speaker comms input does not have 1 and 5 bridged. As far as I could see only the slave input is bridged in this way. I expect I've got it round my neck again.

Streaming: Roon, NUC, QNAP869 NAS
2ch system: dCS Vivaldi, Audionet Stern, Audionet Heisenberg, Magico Q1
Retro system: 101/104/105, Red Rose Spirit