I think I'm going to pull the radio out this weekend and see if there's anything obviously wrong with the speaker wiring. If not, I'll call a Catholic Priest and see how much for an Exorcism.....
2010 Silverado 5.3 3.73 EC Superchip, AEM Air Intake
2013 Jayflight 26RLS
2 Fur daughters
....and empty pockets