The difference between 50 and 100 watts is only a few dB's. The subwoofers have their own amps, so no stress on the receiver. Axiom speakers are very efficient and easy to drive by most receivers. In the past their have been some receivers from Yammy and Onkyo, and a few others that have had issues driving the 80's, but you won't have any problems with most of the current solid state receivers, especially Denon.
A lot depends on your room size, levels you listen to, etc. The 60's and 80's are both great speakers. Also, if you order from the Factory Outlet you save an additional 10%.
