Stock HU to PAC AOEM-MAZ2 to Stock Bose...

I've been having an unresolved issue with my set up. I will give the details. Problem bluetooth phone is extremely low when phone volume to max and radio.

unplugged the bose sub..I am running an aftermarket sub to aftermarket amp straight to the PAC AOEM-MAZ2 to the stock HU. Everything else works good but the bluetooth phone calling. bluetooth music is good and well as gps.

Is there a way to solve this? the stock amp was not touch. I read in some places that you have to tap into the stock amp or bose sub cable.

Your help is gratefully appreciated.