I have a Kenwood KDC-215s headunit that has a rear right and rear left RCA connections. I want to add a little bit of punch to my system by getting an amp and subwoofer. I don't need anything too loud, just to make the music I listen to more enjoyable. Can you guys recommend an amp and subwoofer for under $200 total. And also point me to an amp kit to use with that amplifier?