Just an update on the issue of the repetitive buzz/click noise I was experiencing in the headsets. Jake (Dynon Australia) responded by PM and phone to help me troubleshoot the problem. He even rang me on a Saturday evening at 10:30 pm (his time) - fantastic service! Anyway, after some experimenting (eg. engine on/engine off, different headsets, pilot/co-pilot sides, avionics on/off, A/P on/off, disconnecting the EMS etc) to try to isolate the source of the problem, I found that the noise finally stopped when I disconnected the backup battery. I re-connected it to confirm that the battery was causing the problem. To my surprise - no more noise. Connected everything back up, powered up the system several times, flipped all the switches etc and everything works fine. Don't know what the problem was - maybe something to do with micro-Molex connector, but all is well. Thanks again, Jake.