I think im one of the only people in the world who still has a denon poa-2800. i was pretty damn suprised when i saw this thread.
Personally i really like the Denon. Im getting it back from the repair shop tomorrow, some loose solder connections on the power supply were causing a +5V DC offset.
Good times.
Anyways, cannot comment on the sony, Im using a denon avr 3805 as a pre/pro and the difference in sound using the amp vs the reciever is pretty strong.
I cannot compare it to the sony, but i find the midrange pretty refined in the denon. The bass is great, nice and fast. For the price range i personally think it is a hell of a bargain. I know i will eventually upgrade to something a bit more high end, but for now im completly happy with the POA-2800
System = Denon 3805, Denon DVD2900, Denon POA-2800, JMlab Chorus 707s, Velodyne DLS-4000........