If you have an premium sound system there is most likely an amplifier between the head unit and the speakers. In some models there is a digital signal processing module under the center console. Need to know what sound system is in there.
For some reason I can’t get a picture of it to upload. Google top side creeper and look at the one Jegs sells. They’re great working on these trucks, especially the top of the engine. I bought one for my son, it’s in my garage, sometimes I let him use it lol