Speaker damage is my first thought.
That was my first thought. Not knowing much about stereos I wondered about damage to the amp as well.
To begin with....did u add the Saturn USB head unit? I ask that question because it was only available from the factory as an option in 2009. That being said...u may wish to change your radio settings...it may help. Remember, we have a convertible. Nothing really helps significantly even if u change your speakers...do not install a cobalt USB radio because it comes with headaches.
It is a Sky USB unit. Bought it new off of eBay a couple of years ago and installed myself. Worked great the first year. Noticed the crappy sound late last year and ready to remedy. Can't have a crappy stereo in such a nice car
2008 Sky Redline (Red)
New to Me in 2016