Back to the OP. It's seeing your arm plate on Saturday that led me to do the same thing: I couldn't get enough arm height adjustment with the Mike New platter and the spacers that were used to jack up my Dynavector to overcome the edge between the two surfaces always bugged me. Then I saw that your plate (the same as mine) had been reversed to provide a step-up rather than a step-down in the centre section. Light dawned!

So tonight I removed the arm and plate and reversed the centre section to be a step-up and reassembled it all. Now the arm pillar chuck is bolted firmly to the plate without spacer nuts. I also have plenty of height adjustment so that I can run the Shelter very slightly nose down, as we discovered with your Ortofon that it plays rather well like that.

I didn't expect much improvement to be honest but wowee! It sounds fantastic, with more air and insight into the acoustic of the venue. And, mercy mercy, sibilance is reduced to being no issue at all. What an incredible gain for 40 mins work!