This is where Linn should have had the edge, only they decided to stick with a "blue-printed" TD150 for getting on for forty years..
In the absolute sense, it's how close the turntable system gets to the master source (assuming it's been done with no messing, as some are) and in Linn's case. the Blue Nile 1/2" 30IPS masters they have/had with no Dolby as I remember, sounded absolutely devastatingly good..
What I'm trying to say is that with the SL1210, one kind of arm will get the "system" closer to the source quality and so will a particular power supply designed to work with this motor arrangement, minimising the compromises. If a Rega arm sounds one way and a Jelco/SME sounds a different way, which is closer to what it ought to be? If you don't really know and rely purely on guesswork and opinion, the subjective disasters which are our ears with shedloads of "error correction" introduced by our minds' preferences will rule the day and we'll be no further forward in actually making the deck "better" i.e. as close to the source/cutting session as the vinyl disc will let us get..
It is interesting though, how careful engineering (in the case of a record player) and good knowledge of what's going on seems to get a good subjective quality as well.

