Dave,
I have the 2.3, a slightly harder load, and I have used the Bryston 4B-ST, Plinius SA-102 and now the Rogue Zeus.
I've found that while power is key, the quality of power -- and everything else down the line -- is crucial.
I've had good luck over the years using Cardas Neutral Reference speaker cables.
Good luck with your Thiels. They are a great speaker. I have replaced just about every other component in my system but kept the Thiels. They really reward you.