axiom_man,

I can't help but wonder, why not use the amp inside your Denon? It is rather robust.

Especially for rear and center channels, they don't require much power. The mains are what take the most juice.

Are you considering purchasing a strong 2 channel amp for your mains, and using the built in amp from the Denon? If the Denon is not powering your mains, it will have tons of power supply left for the center and rears.