Hi Isvaldo, yes I have heard the M625 for quite a while in October. The amp replaced a pair of recent production M301 monos that were initially in the system (I believe these were Jeff Rowland's own private pair). M625 had initially 4 hours of music on it.... but Sunday it had perhaps 48 hours of music. The sound of M625 kept developing rapidly throughout the show. Very quickly it exceed the M301 in extension, sweetness of treble, depth of bass, overall harmonic exposure, ease of listening, and solidity/proportions of staging/imaging. Interestingly, the overall size of the stage was not much smaller than what was generated by M301. By the end of Saturday it was magnificent.... by the end of Sunday it was still improving further.
I should like to point out that I have not heard M625 next to an M312 yet, so I prefer not to venture guesses on differences. I am trying to source an M625, so I can conduct some A/B comparisons against my own M312.
Guido