If you're thinking about going the high-quality 2-channel route in the near future I'd go with a good stereo amp and continue to use the 3300 to power the center/rears. Unless you're thinking of upgrading speakers too, you might also consider a higher quality stereo preamp with a home theater passthrough function. This would allow you to use the stereo amp and preamp for serious 2-channel listening while still being able to use the Denon for movies/surround music.
Recommendations for amps would be McCormack DNA-125 or Odyssey Stratos, and if you're interested in preamps with HT passthroughs there are the Adcom GFA-750 and McCormack RLD-1. Incorporating any pair of the above will seriously bring your NHTs to life. You might even consider doing the preamp first...it may make a bigger difference than the amp. I'd suggest finding a good dealer and trying some of these at home before making any decisions. Your best move will become evident pretty quickly. Best of luck.
Tim
Recommendations for amps would be McCormack DNA-125 or Odyssey Stratos, and if you're interested in preamps with HT passthroughs there are the Adcom GFA-750 and McCormack RLD-1. Incorporating any pair of the above will seriously bring your NHTs to life. You might even consider doing the preamp first...it may make a bigger difference than the amp. I'd suggest finding a good dealer and trying some of these at home before making any decisions. Your best move will become evident pretty quickly. Best of luck.
Tim