My 01 Sierrqa with no Onstar has some speaker issues. If I have the balace set evenly within a few minutes the front speakers start getting static in them. Almost acts as if they are "getting Warmed up" then acting up. When i first start the truck in the morning they will sound fine for a short time. Rear speakers are fine. In fact I have to keep it set to the rears all the time if I want to enjoy any music. Any ides?

Sounds like the head unit is no bueno. Time to replace. But its gonna cost you unless you replace with a factory.