Did Denon receivers use Audyssey auto calibration in the past receivers or is this new to the latest versions?
The impression I get is that the Pioneer system is one of the best. I saw a comment by a professional reviewer saying some were not good but they did not mention which ones.
The more upscale Pioneer Elite's have their most robust EQ calibration. The newer Denon's from the 2807 on up have the Audyssey MultiEQ system. I have used both in addition to Yamaha's and find the Donon's and the PE's to be the best. The Denon's have the edge in balancing the room for multiple seating positions.