@dover - for sure. this AC motor experiment will hopefully yield some discernible result.
i did put the motor on iso acoustics gaia feet last night. i had done this previously and hadn't liked it. but i guess i wanted to try again because the logic of it is that the motor as it is produced alot of "chatter" which then goes into the credenza and then into the table etc. if i could stymie that at source perhaps we get an improvement. stethoscope said i was onto a winner for sure. the Gaia feet vastly reduced mechanical noise in credenza.
the music was sublime. it was much improved. i would describe this situation as me having fixed an actual problem. not just a tweak. the problem being the motor chatter being transmitted into the credenza.
the outcome was more range. more highs. more lows. greater differentiation of lows. it wasn't subtle. i am now at the point where it is hard to believe it could get much better. whilst wow and flutter is very low (0.03/0.02) speed variation of 0.2 rpm continues.