Rafa, I meant to say that the difference between the ST-10M and the ST-10 might be less dramatic than one might expect. I see it more as a lateral upgrade albeit better but not substantial enough. Keep in mind we are talking about three competent amplifiers here. But then again I am speculating, having not heard the M or the One. I am old enough though to know that in the audio world terms like "night and day differences", "substantial differences" and "vastly better" are to be taken with a grain of salt.