You'll definitely benefit from giving more juice to the Studio 100s than your Denon can provide. I've got a 3805 and picked up the 100s about 3.5 years ago ($1650 new/pr) and added an Anthem MCA-20 (225 wpc) and have never looked back. Before adding the amp, the Denon ran pretty warm. The 100s, while a very efficient speaker, have a monstrous dip down below 3 ohms in the lower frequencies that gobbles up a lot of juice. They like to run loud, and really only sound great when they are loud, so you'll definitely want to add some extra power. Rotel, Outlaw, B&K, Adcom, Parasound, etc are all very good reputable brands, but for the kind of money that you'll shell out for a new amp (~$1k), you'll either want to make sure you've got a 30-day return policy in the event you don't like the amp or maybe shop around for a used one on Audiogon or elsewhere.
Good luck!
J.