Hello, i have a 08 G37s with the premium bose sound system. I am starting to get a constant crackling noise coming from only 2 of the mid speakers by the backseats. The noise is constantly on, even when i turn off the radio. It is only the two speakers by the back seat on each side. I have never messed with anything audio wise, and interior is completely stock. Could this be an amp issue? It will sometimes go away, but then it will always come back , sometimes louder than usual. I have tried adjusting fade/balance and it does not change anything. Any help will be appreciated. Thank you very much!