Good question. I've always seen those virtual jukebox forums (like over on BYOAC) mention using a car audio amplifier. Don't know if that means I can use the original field-effect speakers, or whether I need new ones.
If I can use the original amp with the great quality I hope for, that would be better.
Mine is a Rockola 450. I already have the touchscreen, software and PC setup. Need to figure out how to mount the touchscreen in the top (probably need new glass cut), then figure out how to amp the music like you're trying to figure out...