Hey guys, hoping some of you might have experienced this before.

Kenwood Excelon X494 (I think that's the number)
Kicker 200.4 running tower (all bridged)
Kicker 700.5 running inboats (cabin speakers bridged on one channel, bow speaker not bridged on
second channel and 10" solobaric dual 2 ohm sub (run in series to get 4 ohm load)
All in-boats and towers at Polk Audio

After several hours of pretty constant play using an iPhone connected via iPhone cable thru USB, I get a tinny noise coming from the speakers whenever a bass note is played. Regardless of volume, and regardless of fade. If I have the tunes faded all the way to the towers, I can still hear the tinny noise coming thru the inboat speakers. It's really really bad at times, and comes thru all speakers. The only way I've found to cure it, for a little while, is to shut the stereo down and let things cool. But, it inevitably comes back.

I have always had a strange high pitched whine coming from my 700.5, but it never affected the sound quality. Not sure if that's the deal, or if it's the headunit, or the iPhone cable. I have run with this arrangement with several different iPhones and it happens will all - so I've ruled out my phone. I'm pretty sure it's not the amps becuase it comes thru all speakers and there are two amps.

Any input from you guys would be awesome!!!