For the Ref Evo, which has been renamed to Evolution One, I've posted the listening impression in the new thread started by Jason. The Evo 1 is just on another level that we will not draw any reference to the ST-10 or Ref 20.
Now the ST-10M. I've updated the website with more info so hopefully there's enough there to get a better picture. And here, I hope I can do the ST-10M more justice. The ST-10M IS NOT just a mono version of the ST-10 on steroids. People who are expecting the ST-10M to be just a more powerful ST-10 will be surprised!
Kudos to the engineering team for taking the effort to not just 'bridge' the ST-10 circuitry with the ST-10M. The whole power supply has been improved, which the ST-10M gains an effortlessness in the musical presentation with everything else up a notch. The layout of the circuitry has been revised for the ST-10M with additional slight tweaks. The overall presentation remains as neutral as the ST-10, while gaining a more full-bodied and richer sound. There's an added smoothness in the ST-10M that is the easiest to spot when comparing against the ST-10. This is not to be mistaken for the warmth of the STA-9 which is based on a different design.
Listeners who prefer a more forthright sound may still prefer the ST-10. My impression was that the ST-10M achieved the right balance between the STA-9 mono and ST-10 which makes it a great upgrade path from both.