Sonically, these two loudspeakers are very similar, but there is a dynamic difference. The M80s do go lower than the M60s, with a bit more snap, and more power, as you noted.
As to the receiver question, we have a lot of experience with Denon receivers and we find them very very good. We feel that they have no problem driving 4 ohm loads, as we drive them very hard in our labs and we haven't ever have a problem with them (and our customers seem to feel the same way).
Ian Colquhoun
President & Chief Engineer
