What is the "correct" VTA for the Lyra Atlas?

I am brand new to a rekindled interest in Vinyl, after 30 years of CD exclusively. In order to save money I have jumped in at the deep end, to try and avoid upgraditis! I have a clear audio Master Solution AMG Wood with CMB, with Kuzma 4 Point arm and both the Lyra Delos and Atlas cartridges.
Initial setup of the Atlas, revealed remarkable sound, could not tell the difference in frequency span between SACD and Vinyl of the same recording, the vinyl just had a more "musical" sound, I suspect fuller midrange, and less hash in the top. In my quest for perfection, I got a Dino-lite microscope and measured the VTA, which was 22 degrees, now the recommendation is for 20 degrees, so i lowered the arm as low as it would go, and managed to get it down to 21 degrees (reset the tracking force), and the top end disappeared, cymbals were not there, started sounding wooly and sweet, much like the Airtight MC-1. So went back to 22 degrees, and I prefer that sound. Now SRA is impossible to measure, because I find it depends a great deal on where I choose to draw the lines, and I suspect on the Atlas, seeing as though 3years, the diamond will be mounted correctly. Lyra are quite specific about the tracking force 1.72g and the VTA 20 degrees, and I do believe they know what they are talking about!! What should I do? My arm has this ability to fine tune VTA on the fly, isn't this ridiculous? I have seen how far the arm has to be lowered to make a 1 degree difference in VTA some 5mm, and since cutting heads apparently vary from 10 to 30 degrees, what possible difference can a changed in arm height of 0.1mm make?
Secondly, when I set tracking force using a digital meter, as I lower the cartridge, the meter starts reading -ve, as the magnet attracts the measuring plate. I suspect the force I have set is too low by a factor of the magnetic attraction?? Is this a valid concern? My work around is to lower the cartridge and then re zero the meter with the stylus just above the measuring plate.
I suppose you can see, I am out of my depth here, and would welcome, any advice.
I vaguely remembered Lyra just said in its manual for Atlas to keep the arm perfectly parallel to the platter for VTA.
SRA on Lyra is difficult and I think on Fremer's site, he mentioned someone trying to adjust SRA to the point where he had to remove rice paper from the bottom which was a no-no.
I tried this whole USB microscobe very difficult to do and it was easier with my arm to just aim for the arm to be parallel then adjust depending on the sound after that.
I do the same think with electronic scale, zero it after
the cartridge is placed above it.
If the top end disappeared then I think it's safe to say you have the VTA too low. ;) Use your ears and determine what the best sound for you is. Same with VTF. If you are more comfortable with a more accurate scale then try the Cartridge Man Digital Scale. It is spendy but it is not effected by the magnets in your cart. It is rechargeable also, so there is no need to worry about replacing batteries.

I have my Lyra Atlas sitting pretty much dead level and it sounds excellent. As for tracking, mine sounds better at 1.74 using the Winds stylus force gauge.

Don't forget the load on the phono.

If set too high the Atlas can sound lean and if set too low it kills high frequencies and dynamics.
when you say frequency span? what are you listening for ? how deep the bass and how extended the highs? I run SACD's and a Lyra Atlas...

I do find the Atlas wonderfully musical, more so than my SACD's...however my SACDs go just as low and as high...
Thank you all for your replies, I suspect I just lucked out the first time, and when I tried to set it scientifically I messed it up. The initial set up was with the head shell, as best as I could judge, parallel to the record. I suspect what all the talk about micro-adjusting the VTA depending on the thickness of the each record, confused me.
Albert your torque screwdriver is great!
If you have achieved a sweet spot where you can enjoy the music and your system ,stop at that point and more important, stop obsessing about any technical parameters. When I got my Atlas I was more concerned about achieving a SRA of 92 % and even acquired a digital microscope from dx.com. Nothing worked. I then set the arm parallel and made very small incremental adjustments and viola I have a world class vinyl set up. I have no idea what the VTA or SRA is and frankly couldn't care less.
Congrats on a world class cart.
Hey guys I thought I would let you know I finally cracked it. Had to make a perspex stand with parallel lines on it to set my Kuzma tone arm level with the record, and it is amazing. The other methods I tried to set the cartridge level, just didn't have the resolution. (Trying to judge the head shell parallel with a spacer.) I can echo Sunnyboy, I now have 2 microscopes the latest has 500X magnification, and honestly I can make any SRA depending on where I draw the lines. Depends on so many things like camera position, and reference record line. As everyone suggested level is best, it was just hard to achieve with a tapered tone arm, and what I thought was level wasn't. Very happy camper now. Why oh why do they make tapered tone arms? At least put a line down the middle. I now wonder if it's worth getting an Oscilloscope to set Azimuth and anti skate perfectly, because I still can't track the last cannon shot in the TELARC 1812, if I remember correctly the Delos had no trouble with this. Any suggestions would be welcome. I have removed all damping, and have antiskate set to minimum. Seem to get distortion out of L and R speakers at the same time on test records.
One parameter that will absolutely affect tracking performance is the effective mass of the tonearm. It may look crude, but adding pieces of mortite / blutak to the headshell is a good way to adjust effective mass.

Unfortunately this method only allows you to add mass, not subtract it.

You may want to ask Kuzma what the effective mass of your tonearm is, so that you can quantify your results as you experiment.

FWIW, which microscopes did you settle on?

hth, jonathan carr
Jonathan, Thanks for the suggestion. The arm is a 4 point and I believe the effective mass is 13 grams. I am not using any damping at present, perhaps I should try this as well.
The first digital scope was the Dinolite(200X), the most I could achieve was about 150X magnification because the diameter was large and therefore I could not get it close enough to the stylus to focus at higher magnification. I then got a Supereyes (500X) which has a much smaller diameter and can get in close. The software was not very good with the Supereyes, and I was unable to import the pics into the Dinolite program, which has easy to use measuring tools. So next was a print out on A4 paper and a protractor. In the end I gave up. My SRA was anywhere between 96 and 94 degrees depending on where I drew the lines. Now that the arm is truly level the base is even higher than when I did the measurements. The trouble is that there are so many variables with the photograph and the measuring, I think the results are likely to be misleading. everything has to be exactly 90 degrees and parallel, and the most difficult thing is to define the surface of the record or CD in the plane of the cantilever, or at least that is my experience.
When I tried to set SRA I was missing the highs and the bass was a little overwhelming, now the detail and highs are spectacular, and with that imaging, depth, and sound stage are all superb. Some real experts in the States measured my photographs and came up with 94 degrees, so I was convinced I needed to lower the base of the arm more. Now I can hear that it is "right", which was what everyone was telling me in the first place, my photographs must have been skew! Garbage in garbage out:)