Dear Rauliruegas, Thuchan's thread started with a question about a quality that can't be measured and his emotional reaction to the EMT 927, so yes its all subjective. You bring up a few different points and I want to break it up and answer you to the best of my ability.
1- What we have here with the 927, American Sound and others isn't something that you can capture, put in a bottle and sell, it goes way beyond measurements. This is a musical interment designed and fabricated by someone who was an artist and an engineer. What is it makes a Stradivari or a Guarneri so special. If you see theses instruments up close, there's nothing special looking about them. They're dull and utilitarian yet they have a magic that no one's been able to explain, measure or reproduce. You can hear it and you'll feel inside you, its there and its real but how do you qualify or measure it if not subjectively? This is exactly what you have with a 927. The EMT 930 is a fantastic turntable and a near exact smaller copy of the 927 but it doesn't share that special quality that we're trying to define with words here. This isn't BS or illusionary its there and its beyond the norm.
2- Measurements are important but in this and they play a part for sure but they can't explain things. A HT subwoofer might measure down to 16hz or lower but is it the same 16hz that you get from a great pipe organ? They'll measure the same but subjectively different!
You mention the SP10MK3, wonderful table, very good sound specially with the heavy obsidian. It measures great too but at the end of the day it lacked that special something that makes the others great. Mosin briefly discussed EMT's motor and I'm sure that its part of the overall recipe as is SP10's motor. That speed stability of 0.0001% you is achieved by its motor, which is part of why I don't care much for the SP10. They achieved that fantastic figure with a servo controlled motor, what that means is that the speed of the platter is continuously monitored and adjusted. This constant tweaking creates certain sonic artifacts that don't occur with an inertia driven system and a non-servo motor, where the platter spins continuously and seamlessly. Granted the SP10 was one of the best of its kind with less noticeable artifacts than the ordinary servo controlled motors but they're still there. So this fantastic measurement which on the one hand tells a story of greatness also creates some of the major shortcomings of the table. My point here is that the measurements serve a purpose but at the end of the day my subjective experience is the final determining factor for me.
3- "Engeneering must be reflected on accuracy characteristics against what is in the market, especially when we are saying that the 927 is the " holly grail ". Maybe you can put some " light " about."
The quality engineering is all there and that's only part of the story. The character at work here is extremely rare you can't just quantify it and measure it when there no comps. The best I can do is to invite you for a listen.
4- "Natural from your point of view and your examples posted is more a subjective parameter that means it's not neutral but only diferent with different colorations/distortions."
No, I never said anything about colorations and distortions, Natural means just that. Its a sense of realism portrayed these tables. As a matter of fact its exactly the opposite. There's no overriding tonal character here, every recording and performance sounds distinctly different. The only constant is reality. Real person, real instrument, real performance. I don't hear additions or omissions of character but that's always subjective too. We have no way of knowing what is in those grooves, only what I hear sounds and FEELS real and its different from disc to disc.
5-" I never had the opportunity to heard the 170 kg. American Sound TT that's a different kind of design including its drive mechanism but I heard the Final Paruthenomn( 140 kg. ) that was an assualt to the state of the art on TT."
The Parthenon was an assault but didn't get all the way there, too many gimmicks. Its not only mass here, The American Sound Table is a minimalist design, a purists dream. There's nothing extra here, every element serves a purpose. Its brutally simple and I think that's why i think it sounds the way it does.