I would probably start with upgrading your sub as the above poster recommended - that's definitely a weak spot in your system. As far as processing and amplification are concerned, there are lots of great options out there. PM me if you would like to discuss specific brands and models - I run an A/V integration company in Atlanta and would be glad to work with you in finding a good setup within your target budget.
Best regards,
D. Campbell
President - Southern A/V Direct, LLC
Best regards,
D. Campbell
President - Southern A/V Direct, LLC