Boom audio Issues on my Road King Classic

I have a set of boom audio speakers on my Road King...the handlebar mounted style. Occasionally, the sound cuts out almost entirely for no apparent reason. If I turn up the volume on the boom audio really high, I can hear a fiant, but distorted sound. It started happening after I took a 30 min ride in a heavy rainstorm. Since then, this will occasionally happen at the beginning of a ride, sometimes at the end of a ride - there's no apparent pattern to when/why it happens. Sometimes it will begin working again normally for no apparent reason. The one constant is that the green light on the hand controller always stays on, regardless of the quality of the sound, unless I manually turn it off.

A friend of mine told me to simply check the ground on the bike and ensure that it is secure. Other than that, which I have not done yet, what else should I check out when I begin investigating the problem?

Any assistance pis GREATLY APPREICATED!!!