Emerald Physics and Tube amps?

Considering trying a tube amp with my Emerald Physics CS3s (95db efficient). Since this is essentially a bi-amplified system (Behringer crossover feeds a powered sub) the tube amp would only be powering the coaxial mid/high driver. Has any EP owners out there went the tube route? Would appreciate your thoughts and experiences. I find the CS3s to be all I've read about and certainly was so impressed with what I heard of them at RMAF 2011 in October ended up buying a pair. They are kind of like a blending of two other speakers I've owned in the past, the Martin Logan CLS (extreme clarity and speed) and the mighty Klipschorn (dynamics and emotional impact).

Also, on the tube front, how much is enough? Would a 6 watt SET be a good match or go for something with a bit more power? Thanks in advance.