Whining noise coming from 2015 G23 speakers

[taylorcuse]

Hey guys,
I have a 2015 G23 with a Polk Audio system. When the boat is running for about 30 minutes, (we timed it) the speakers start to make a really annoying, loud pitched whining noise. When the engine is turned off, the noise soon goes away. The tower speakers are making the loudest sound. We haven't had any issues other than this, but it's really annoying and hard to bring friends out with an annoying sound in the background. Any ideas on how to fix this?
Thanks for the help,
Taylor

[Stevemo14]

Sounds like a bad ground somewhere to me. The noise is probably coming from the alternator charging the system. Why it would start after 30m I have no clue, unless it takes that log for the ground to heat up and not conduct properly.

[MLA]

Am I reading correctly, that the noise is omitting from all speakers, but the tower speakers are the loudest? If so, this points to an issue upstream toward the media source unit. To prove this, with the system off, disconnect the RCA cables from the amps, then power the system up. Just note the RCA's locations for re-connection.

No more noise = issue. Noise returns = noise is generated at the amp level.

Start there.