Interesting stuff, I hope Teres comments on it. My own question at this point would be, what proportional contribution can we ascribe to the control system implemented on the DD, beyond the mere fact of the drive method itself? My own hunch is that this is where the greatest theoretical advantage of DD may lie, in affording the possibility of precision-designed platter control...
BTW, in response to two points raised above: I suspect resonance is probably still somewhat more sonically determinative than speed distortions in modern high end designs; and when Twl writes:
"I think it is because turntable designers all have varying degrees of understanding of the entire turntable system, and place varying amounts of emphasis on "perfecting" the various aspects, within a certain price range, and possibly with different technologies and approaches.
It is definitely not a foregone conclusion that just because a company makes turntables, that they are "expert" in the field. And even "experts" have holes in their knowledge base. And even if they do know everything(impossible), they cannot implement perfection, or even close to it at any affordable price range.
So, what you buy is inherently a compromise.
What types of compromising, and how well the compromises work as a whole, will determine the results"
that about says it all, and if anything may be understating the case. With the proliferation of TT's these days, and especially moderate-to-mid-cost ones, my guess is that plenty are not really comprehensively "designed" at all, just aesthetically pleasing combinations of common elements, made and marketed to price points with full knowledge that they will never be technically scrutinized by the audio media, only subjectively compared to similar offerings.
