Darth, either of those receivers should have plenty of maximum power capacity for sensible sound levels. Choose on the basis of features and price. A factor in favor of the Denon is that the Audyssey room correction system is widely considered to be a bit more advanced than the MCACC on the Pioneer.
Dakmart in general doesn't have a very high customer satisfaction rating. However, I assume that you're considering them for a Denon factory refurb(they're an authorized dealer), and it appears that they handle that area well, possibly because of fear of losing the Denon business.
