Small amp and 6 1/2" speakers hidden in the trunk with a Bluetooth interface ($30). All hidden with clean and simple wiring. Syncs to iPhone/Pandora in seconds. Gives just enough noise when cruising. Mine are mounted behind the rear firewall with the carpet covering the speakers and acts as a speaker grill. Very stealth. Can't post a picture because you can't see it
I don't recommend ear buds at all. A bit to disconnected from your surroundings for my taste. Just my opinion.