2006 Trailblazer Bose Amp Location

Don't quote me on this but I believe the amps are on the speaker pods.

Well with the fronts that's true.  Not with the rears =(.  I'm assuming there is another AMP somewhere that drives the rear speakers sine they both have this noise and the fronts dont.

The problem is likely not due to the amp's ground. If this vehicle is under warraanty, you must take it to the dealer to repair otherwise you void any warranty on your audio system. If the truck is an extennded version, the amp is under the driver's rear window above the wheel well, behind the trim panel. If it is the regular version, the amp is in the same area, only on the passenger side. There are two common problems on these trucks. Under the seat behind the driver seat there is a flap of carpet inboard of the BCM/fuse box. Disconnect the plug and reconnect it. It may be a bad connection and this should fix it. It could also be a pinched harness going to the amp. It gets pinched by the rear seat bracket where it bolts to the floor by the passenger's rear door. sparky