One of the people I setup a system for called me and told me that "all of a sudden" every time he presses a key on his mx-980 he hears a loud sound coming out of his speakers. It is an RF setup using an MSC-400.

I am going over this weekend to check it out. Has anyone seen this and could advise as to what I should look for?

I am half expecting to see an emitter wrapped around a speaker wire or something.