I have a Videologic Digitheatre DD 5.1 and am currently looking at upgrading this. I am thinking about getting a new amp but keeping the speakers and sub that came with the digitheatre. First of all is this possible and what improvements will I get from a more expensive amp. Would I need new speakers as well. I have a relativly small room 9 x 12 feet. I have a budget of about £500. I also need speakers to be quite small as i don't have much space.