We got a UE Boom2 bluetooth speaker that is shaped to fit into a cup holder that sounds great. I mounted a cup holder for the speaker on the cart frame just below the roof behind the driver and no one can see it unless really looking for it. I also use the Spotify app on my phone as a music source and love it. Also, there is no real need to install a USB port for charging devices, just keep a portable back-up power cell handy if a quick charge is needed.