i just installed a new sony aftermarket head unit into my 02 tahoe. also put in 2 10" subs. i am having an issue with the head unit. my radio will play just fine door speakers subs and all. but when i change it over to aux or cd player all i get is sound out of my subs in the back. was wandering if someone has ran across this same problem and what i can do to fix it. thank you