G, your barking up the wrong tree. In both cases the sounds work when the engine is addressed. They are just noisy before the fact and sometimes come on when not addressed. If there were no sounds when addressed then there might be a problem with the serial data line but that doesn't appear to the case here.
I would ask both posters to look at their audio power boards and check to see if there is a metal shield around the toroid coil. The early boards did not have these and could cause interference with the R2LC signal.
Pete
