One of the interconnects may have a problem. Try swapping them between channels.
Otherwise it is probably something inside one of the components (most likely the receiver, as they are pretty crammed with stuff.)) just too close together and a 'leak' of radiated energy is causing the noise.... Could even just be a wire too close to the cucuit board.
These are my guesses.
Otherwise it is probably something inside one of the components (most likely the receiver, as they are pretty crammed with stuff.)) just too close together and a 'leak' of radiated energy is causing the noise.... Could even just be a wire too close to the cucuit board.
These are my guesses.

