Well, my friend has Montana SP II (these are now discontiued) & he drives his speakers with RAM Labs (Roger Modjeski) RM-9 with great results. The EL34s have a really nice midrange.
I visited somebody else last Sept. who owns the Montana WAS speakers (I've never seen such a huge loudspeaker in a home environment!!) & this fellow was driving his speakers with PBN/Montana's Sierra Audio's amp. He had 2 of these amps so it was a mono block config. The amp that he is using is not yet on the PBN website - it was a bigger amp than the Everest. The name escapes me right now but I have the electrical schematic & discussion on it @ home. I think that this fellow has a late beta prototype. Something like 400 or 500W/ch, class-A. Super expensive (well, this guy had some money to throw!!).
Looks like the EPS are 92dB efficient so you could get away with a 100W/ch type amp. Try to get hold of a pure class-A amp (maybe the Sierra Audio Denali?) or a Pass Aleph or something else. You won't regret it! The class-A amps have a certain magic.
