Is VTA and SRA the same thing?

What I meant was since the lps have different thickness and some other variables, using microscope to find the 92 degree is only bring you to the boundary of 92 degree, therefore if we can trust the cartridge manufacturers we can save money on purchasing the microscope.

if we can set the top of the cartridge perfectly parallel to the platter, then we can get very close to 92 degree?

If all is well, probably so. But I've seen cartridges where the stylus was incorrectly mounted, making the proper SRA impossible. It never sounded right either- finally traced the issue to that defect. So sound quality is a good indicator :)

Correction: "parallel to the LP surface"

Dear @dangcaonguyen  : Please forgeret about that 92° that is what says theory. Trust in your ears that let you know your reality ( an non-perfect reality that can't even theory. ), what you like.

R.

Fortunately Atmasphere I have not seen an incorrectly mounted stylus for a long time. I always view a new cartridge under magnification to make sure the stylus is generally in the right position and shape before I mount it. In the old days, late 60's early 70's one in three cartridges would have an incorrectly angled cantilever or wacky stylus. Hopefully this is not going on with today's inexpensive cartridges. The more expensive cartridges have been excellent in my experience.