Good question and I will answer carefully

.
The Denon has the better build quality and I believe better DACs.
The Denon has better video.
However, to compare a modified 563A w/Bybees to a stock Denon is a tough call. I have not done the direct comparison yet, but i do have a stock 2900 and a modified 563A so I will try to do this listening tomorrow.
The other thing is that I am finallizing a power supply upgrade for the Pioneer 563A and most OTHER Pioneer units as well, that will significantly improve their performance by getting the audio circuits away from the stock switch-mode power supply.
Please stay tuned...
Dan