another strong vote for rel sub pairs, using the high level (speaker) connection -- wonderful match easy to integrate
but in a small 11x13 room, a single rel should work fine
parenthetically, i recently tried (due to the all the youtube talking heads' groundswell) a pair of svs micro 3000 subs... with their fancy cellphone control app etc etc... these subs only use preamp level inputs, there is no option for a speaker level connection -- this experiment lasted all but 48 hrs, the cute lil svs's were unceremoniously kicked to the curb, back in went my rels