I recently put in my sound system in my new truck with Bose, I am using the AP4 GM61, I just pulled everything from my old truck and put in new one and everything seems fine except the bass, it's non existent until I have the bass knob turned 3/4 way up and by then it sounds muddled or too much especially at medium to lower volumes. The module was installed by a stereo shop in the previous truck and I do not know what all configuring they did which might of been none cause the chime volume still about pierced my eardrums. I did set the " minimum volume " and wonder if that messed it up. The chime volume is perfect now after I set it. I am thinking or setting back to factory settings but don't know how good it would sound like that or if too difficult to try and tune with a PC. Is there a certain position to have the knob while tuning the system? Thanks in advance.