Thanks for the input,

I changed the comms setting on AUX source from -C/1A to 4C/1A as suggested, but no change.

MC200 settings are Sys 1, Product 1, source 4.

If the G91 is set to AUX and you first press play tracks now on MC200, it also causes G91 to change to "TV ", but if you reset G91 back to AUX, it stays on this selection, provided you don't mute the volume.

MC200, G91A, DSP5500, DSP5000C ,DSP 3200