Here's another vote for the AudioControl Maestro M9. The analog 2-channel mode on it is amazing. I put a ~$5k Bryston BP-17 preamp in front of it running in HT bypass and it did not sound even a tiny bit better than the Maestro M9. I returned the preamp. A $9k Atmos processor beating a $5k 2 ch preamp -- that tells you what Troy is so excited about.
Dirac on the M9 is very effective once you get it running but it's a nightmare to use due to the Windows interface which was apparently designed by a drunk and angry toddler. Sounds great though.
As an alternative to multichannel amps I use multiple stereo and monoblock amps. A Bel Canto monoblock for center, two of their stereo amps for the dolby surrounds, and two Crown stereo amps for the Atmos channels. These amps are all Class D, take up not much more space than a big multichannel machine, and can stay powered on all the time.