My room is 35 x 35 x 9, and my 4802 gave me all the volume I 'needed', but I like going beyond what I need occasionally. I would say your Denon takes you 95% of the way to audio zen, and external amplification squeezes out the last 5%. I totally understand why most people don't feel inclined to pay so much to extract that last 5% out of their system. But it's also my belief that once you do experience that last 5% of performance, it changes your outlook on the equation as a whole. It's not 100%, but a very good percentage of those who take the plunge never look back.
But honestly, external amplification is like icing on the cake, at best it's the very last step you want to take. Once you have everything else dialed in, then add more power if you still want it. Outboard amps aren't a cure-all by any stretch of the imagination. If you're having issues with your system more power isn't going to fix anything. If you think it through logically, more amplification is only going to take whatever audible problems you might be having, and amplify them... right? So don't think of separate amps as a solution, think of them as taking a well sorted system to another (volume) level.
