I am going to get a new work truck and i am out on the job site at lease 2-3 times a week. I am wanting to continue to listen to my music while i am out of the car. I was thinking of getting some marine speakers and mounting them in my canopy but the problem i run into from there is i do not want them to be playing music every time i turn the radio on, only when i am not in the car. is there a way for me to hook up a switch so that when i flip it the external speakers turn on and the internal ones turn off. or is there a way for me to just turn the externals on and off while the internals just stay on like normal.