which valve amp for Forte III or Heresy III?

Well the Leben looks like an excellent choice plus you’ve already heard it and according to you........there’s something magical about it. How can you beat that?

thanks so much!

both of those speakers will benefit from higher tube power despite their published specs. 

something KT 120 based like the Rogue Audio Stereo 100 would be awesome.  

Out of those only heard the Octave. Wonderful amp IMO! Also would have the balls for less efficient speakers should you ever try something different. 

The best tube sound I ever got was from my Triangles and not my Heresys. If not Triangles, perhaps something from Focal. I put about 5 different amps on my Heresys and they all sounded flat. 

My second system includes a Leben CS-300xs driving Forte III's and the synergy is fantastic.  I have tried pairing the Forte III's with a Cary SLI-80HS, Luxman MQ-88uC, and Sugden A21SE and the Leben pairing is far and away the best.

I now have a Rogue Atlas paired with my Heresy IV's. I am simply in awe every time i sit down. It's such a harmonious combo. Everything has opened up, soundstage, dynamics, depth, sweet midrange and treble, weighty lows. I like switching between Ultra, and Triode. I never thought anything could come close to my MAC 240 in my price range... but here I am. Seems there are plenty of reasonable options second hand here and elsewhere. On another note, I was very intrigued by Rogers, just slightly out of my range.

Cheers