With a line contact stylus tip, azimuth and anti-skate are very critical settings.
If you have this loupe, or equivalent, you can set it up on a record that has some non-recorded area. Place it on the record and in front of the cartridge. You'll be able to see the stylus tip and its reflection on the record. When the stylus tip and its reflection form a vertical line, the tip will be perpendicular to the record and azimuth will be set correctly. In my set up, when I set the azimuth with this method, I get no sibilant issues whatsoever.
As for the anti-skating, I used the Hi-Fi News Test LP. This helps with better focusing of the sibilants.
I recently took delivery of Dr. Feickert Adjust+, but I have not set it up yet. Once I do, I should be able to verify if I was off with my settings.
Best,
iSanchez