Dumb VTA Question

IMHO there is nothing wrong with the OP's procedure.
If you can't hear the difference it is not important, if you can hear, then you have done the alignment. The USB microscope may give you a closer starting point, but that all folks!

VTA depends on the cantilever angle, angle of stylus A_N_D what kind of Diamond is used. The side walls have different cuts (and more...) and they track the information. So it is logical that every change in that "angle" will give you different results. some record collectors say, you simply have to dial it in, until it "settles". You can hear it. Another chapter is the cutting angle from mastering...
The VTA adjustment is necessary when you listen to older records (until the end of 60's), when you use an old Mercury/London/RCA ... you can hear how the soundstage gets wider and deeper.
The SRA explanation is another - different - chapter and also has influence to VTA adjustment. But the VTA adjustment is only the way to get the angle the older records were cut for proper reproduction....
What you have done to find a good result is right, but to repeat it again, a VTA at a "given angle" is wrong, the given angle is for SRA and a statement from M. Fremer which sounds important in discussions but is totally overrated in reality.
It is ok when someone uses an Arm which can't be adjusted in the height, when he also uses an arm which is perfectly aligned from arm board to record surface distance (level) and when he listens only to records which were done after 1980 and when the cartridge height overall fits also for level adjustment with the given cantilever length, angle...and there are some more...it may be ok when someone uses a table AND a matched Arm from a Manufacturer ... anyway, forget it and do it the way you did before

In reality, everything affects everything. You aren't done when you change the height of the arm..you must recheck how the raising/lowering affects the downward pressure. Once that is adjusted, you must make sure the stylus still sits in the absolute correct spot of the alignment gauge,...and then understand that all of that has to be checked and adjusted again, and then again, until gradually you are satisfied and can walk away (for a long drink and well deserved rest).

Excellent post by Jcarr. As usual.:)

"However, as I recently wrote in Stereophile, the
construction of every tonearm that I am aware of (with the
sole exception of the Eminent Technology linear trackers)
guarantees that altering SRA will simultaneously cause the
effective length to change, along with the tracking force.

To make sure that any SRA-induced audible changes are truly
attributable to SRA rather than sundry alignment shifts that
came along for the ride, you must recheck the overhang and
tracking force and "put them back" to what they
were prior to the VTA change.

At the end of the day, you may ponder about the real value
of "VTA on-the-fly" mechanisms (grin).

kind regards, jonathan"

I would just like to add that IMO overhang should be the
last adjustment done after changing the other parameters. We
could argue the order but I think it should be SRA first,
then VTF, and finally Overhang last.

Then there is Azimuth. If you have a linear tracker or a
pivoted tonearm that adjusts Azimuth in the same plane as
the offset angle then adjusting Azimuth should not effect
the other settings much at all. On the other hand most
pivoted arms adjust azimuth at the back of the arm.This
adjustment is not in the same plane as the offset angle.
When this is the case, changing azimuth will effect all of
the other settings (VTF,SRA, and overhang). In this case I
would do it in this order. SRA, Azimuth, VTF, and then
Overhang.

As said above, this needs to be done multiple
times by ear to dial it in.

Sean