I have an 06 that was installed with the GROM BT3 unit. Everything sounded amazing until a couple weeks ago. At first I thought my front speakers were trash but upon listening closer, ALL my speakers sound like the bass has been blown. I also hear a new rattle noise (sounds like it is inside deep near the CD player) when I start up the car, but only upon start up. Seems suspicious. I believe I have the premium sound but I don't know that for a fact because well, this is all new to me. I know it has an amp and the GROM unit in the back and a CD player up front. Any advice on where to begin to troubleshoot? Seems like it could be a connection issue. THer horrible sound is driving me CRAZY.