I am looking of a modest sound system for my dorm, which will mainly be used to listen to music. I listen to mostly rock, metal, some rap, techno.  I have already bought a pair of Micca MB42 Bookshelf Speakers, and a topping tp 21 amp. However I am beginning to question the topping tp21 because the SMSL SA - 50 is around the same price, but it can deliver more power per channel. Now I am looking for a subwoofer for the system, in the range of 150 dollars. So far I am considering the Dayton Audio SUB-1200, and Pioneer SW-8MK2. Any help is appreciated.