DaVinci tonearm and azymuth

Essentialaudio - agreed. That is at least a suitable option - if kind of archaic with tonearms asking $5k to $11k in retail price.....

If the post is not vertical, I think the shim should go between the post collar and the armboard. However if the headshell is the problem, I think the shim should go between the headshell and the cartridge.

Well, if the arm post is not vertical........ I would suggest changing either armboard, tonearm or hobby.

:-)

 
You're no less an audiophile if uncertain about your ability to detect single digit decibels of difference from vertical perfection. To confirm a setting or what you hear azimuth-wise, you can measure the differences in channel output with a voltmeter and test record.
 
Check this thread:
How to measure crosstalk

One place to find the Cardas test record

You can compensate for channel differences in cartridge coil voltage output by getting a level set for each channel then adjust the output with your preamps L/R balance control.