Please Help! I have a 2014 cx5 GT with the Bose system. I have two issues one my subs are good but barely work in the mazda and two I get the hum that starts low and gradually gets louder when I turn the car off. Any experience or advice? Would like to trouble shoot before taking it to a shop. Thanks in advance for any suggestions.

Does anyone have any advice? Newbie here and it's my 1st Mazda.