Use the Bose® 351964-0010 B1 bass module to add to your L1 model I or L1TM model II system. The bass module output of the power stand can adequately drive one or two B1 bass modules. Up to two more B1 bass modules can be added to your system by using a Model A1 PackLiteTM power amplifier connected to the bass line output of the power stand. The B1 bass module can be placed vertically or horizontally on the floor next to the power stand. When placed horizontally, you can build a stack of up to four modules!