That Denon is likely perfectly adequate, and has real bass management should you add a sub. Sure, it will have features you don't need for a simple stereo rig.
It's difficult to compare the specs between the Denon and the NAD. Power difference is insignificant, so it really boils down to features. I don't know if that particular NAD has it, but some of the Masters series had a spectral tilt tone control, and pretty extensive eq capability. Is that sort of thing important to you? More than, say, bass management?
Were I in your place, I would keep the Denon and instead reallocate the ducats for the NAD to a sub.
