Emerald Physics CS3 question

Hi All,

My Behringer is kaput, bass distortion. What is the best way to improve the bass. I am considering the following...

a Bom, the DSpeaker, the DSP 2.4 or just a subwoofer. I am using a Manley iPod. At present time I am using  just  speakers. Do I need DSP or just a sub. The Manley has a tape loop and sub out. Any Ideas. Room is 13 x14. Someone gave me a DSP 2.4 but I cannot seem to get it working. Does it need a power source.

Thanks