Just installed Rockville sub https://www.amazon.com/Rockville-RW8CA-Profile-Under-Seat-Subwoofer/dp/B019Z3RFGY/ref=sr_1_8?s=electronics&ie=UTF8&qid=1510849970&sr=1-8&keywords=rockville+8%22
I am 56 so enjoy quality. this provided the bottom end I was missing.