Thanks for your inputs. I did visit the audio-database site and see all the information there. I can see that the M10 is a much later product than the M4s (M3 too but not M5) and it's priced lower than the M4s. However, specs wise, the M10 is much higher (better?) than the M4s, THD, Damping factor...Due to lacking of informaiton, I cannot compare them to the M5 or M7 to see if that really mean anything. A photo of the internal M10 to share and all I can say is: stunning...