Swap in different input cable or swap them L to R and see if it still does it. Leave that channel disconnected from the input, does it still buzz? Swap L-R again at the Processor and see if the noise moves.
Thanks! I unplugged the power cord from the 5000 overnight. I then put the speaker cables back on the 5000 from my AVR...no buzz. Switched around the speaker cables to see if buzz was present anywhere...still no buzz. Don't know how, but the buzz went away simply by unplugging the power cord. Weird...