Terry, I don't know of such links, but Denon took the old Panasonic 'RP56 and upgraded the audio section. Of course, the 'RP56 doesn't play DVD-Audio tracks. I would imagine that the audio section (analog output stage, for example) for the '1600 is better than that of the 'RP82.
While they do have different audio DACs, both players have identical video sections, including Panasonic's top MPEG decoder, not the one used in the RP-56.