What a AVR can do is filter out the low frequencies that the speakers are playing which should be going to the subwoofer. This takes a load off the speakers, since the low stuff is most taxing on the drivers. How much of a difference it makes depends on the speakers and what kind of stuff you listen to. If the content you like has deep bass, might be a good idea to filter that out from the speakers. I would say its worth it to move from an integrated amp to a nice AVR not just for bass management, but also for room correction equalization, and other features which AVRs have that integrateds do not- even if its only for a two channel system.