Intermittent sound drops are usually the result of a loose electrical connection, right? I don't hear any buzzing or humming and the drops seem totally random. Loud noises or vibration don't seem to correlate to the dropouts, which makes me wonder. I would think a loose connection would always drop in that case.
I'm sorry for not being clearer. It's an mp3 player (which plays fine all the time) plugged into a mixer and out to stereo speakers. The right speaker drops out.