Subwoofer suggestion

Hi,

I have a pre-amp/amp 5.1.2 setup with 200w amplifiers and B&W Speakers/Sub. Currently I have the B&W ASW610 subwoofer and looking to upgrade it to DB4S. I don't go very high in the volume and even for the current subwoofer, I feel that I barely scratched the surface with the bass. Is upgrading worth it? What difference will the DB4S sub give? 

Appreciate your suggestions.