Well first its important to understand bass is stereo not mono, and one subwoofer (unless its crossed over very low to complement a full range speaker) will collapse the soundstage. Thier really are two options, of course getting a full range speaker with enough bass on there own to satisfy you or getting two subwoofers one for the left one for the right. But to get quality bass information, carefull choice in subwoofers, cross-over adjustments, and placement are critical. It is definitely more difficult to acheive good sound with subwoofers then placing a pair of full range speakers. This takes someone with advanced setup skills to get right.
Kevin
40 years hi-end audio video specialist
Kevin
40 years hi-end audio video specialist