Speaker, amps, sound processors.... Oh I'd better not start on mine.... years ago I ran a Pioneer head unit, multi disc changer, 4 amps, twin sound processors each with an amp per output and 24 speakers, two sets were separates multi channel speakers with their own crossovers for bass mid and tweeters.. The rest were all in ones with bass mids and tweeters. Didn't want or need subs and was like wearing a pair of headphones. Oh but fond memories! And that was in a "normal" car.