Dirk, You wrote, "The Technics SL 1200 GR2 no longer uses a quartz-controlled motor. It is far more advanced and efficient, utilising delta-sigma modulation: the turntable employs delta-sigma modulation (familiar from the 1-bit digital-to-analogue conversion in Technics amplifiers) to generate the drive signals for the motor." As I understand it, delta-sigma control systems often if not usually use a quartz reference. So it may be that Technics has added the DS system and is regulating it with a quartz oscillator.
You also wrote, "This digital signal processing drastically reduces minute inaccuracies in motor rotation (known as cogging) as well as electromagnetic vibrations." Does the digital processing reduce cogging or does it reduce "inaccuracies in motor rotation", because cogging is one source of inaccuracy, but there are others? Further, wouldn't the very fact that the motor of the G and G2 series is coreless be the most effective means by which cogging is reduced in this series compared to the prior SL1200 series, which used a conventional iron core motor?

