Sometimes it seems that an entire comm. system is rendered worthless by hooking up Sony CCUs. Particularly M series multi-core CCUs like M5 and M7.After a great deal of effort working on a 3 camera system with D50s, D50 CCUs, and RTS intercom, and consulting other engineers, I would have to say that the Sony comm. system should be bypassed. They are just doing something different, and it doesn’t seem to play right, even though they claim it is ‘RTS compatible.’ I would suggest running XLR to camera positions, or modifying cameras and CCUs to use the existing wires in the multi-core cable to pass the RTS signal through the camera mic. XLR jack to a beltpack.