In my truck, I have a Custom Autosound head unit with receiver, cd player, usb, aux, blootoof....all that stuff. It's a 4 channel unit. I have a 6 1/4" coaxial speaker in each door and a 200w powered Blaupunkt 8" subwoofer behind the seat. It's a two channel unit wired in with coax cables. It has "volume", "crossover" and "phase" knobs. I've never gotten it to sound what I would call "real good" the whole time I've owned it. It started acting up awhile back and I removed it and put 2 6x9 coaxial speakers in 6x9 speaker boxes its place, but they sounded like infected dog butt. I found the reason the sub was acting up. The RCA connectors had some green corrosion on them. I cleaned them all up this morning and put the sub back in. It's working "good as it ever did" now, but I know it could be better. Now, I know nothing about what I'm doing, so break it down for me in stupid talk so I'll understand. lol I do appreciate any help. Thank you drive through.