Vinyl heresy-overhang induced distortion is not that important


I have learned and am of the opinion that the quality of the drive unit, the quality of the tonearm, the quality of the cartridge and phono stage and compatibility/setting of all these things (other than setting overhang) and the setting of proper VTF, VTA, SRA, and azimuth are far more important than worrying about how much arc-induced and overhang- induced (the two are related) distortion one has. I learned this the hard way. I will not go into details but please trust me-I am talking about my new ~15K of turntable components for the deck itself and excluding cartridge and phono stage. I have experimented with simply slamming a cartridge all the way forward in the headshell, placing the cartridge mid-way along the headshell slots, and slammed all the way back, each time re-setting VTF, VTA, SRA, and azimuth. I would defy anyone to pick out the differences. I have 30K of tube separates, a Manley Steelhead, and DeVore O/93's. I submit that any differences in distortion due to sub-optimum arcs and deviations from the two null points and where they are located (those peaks in distortion) are masked several times over by distortion imposed by my tubed gear and my loudspeakers. To believe that your electronics and loudspeakers have less distortion than arc-induced distortion is unrealistic. I have heard startling dynamics, soundstaging, and detail with all three set-ups. It is outright fun to listen to and far preferable to my very good digital rig with all three set-ups. 
My point is that getting perfect alignment is often, not always, like putting lipstick on a pig, I think back on my days on owning a VPI Classic and then a VPI Prime and my having Yip of Mint Protractors fashion custom-made protractors for each of these decks and my many hours of sitting all bent over with eye to jewelers loop staring down horizontal twist among parallax channels and getting overhang on the exact spots of two grids and yet never hearing anything close to the level of sound I get now. Same cartridges, same phono stage, only my turntable/arm combination has changed. I kept thinking the answer had to be in perfect alignment when it was clearly everything else but.
Thoughts? I am sure I will get all kinds of flack. But for those that do tell me I am nuts, try my experiment sometime with a top-tier deck/arm combination and report back. 
128x128fsonicsmith
fsonic et al, What is measured is the tracking angle error, the degree to which the cantilever deviates from tangency.  All the plots I have ever seen plot distance from outer groove to inner groove as a function of the angle by which the cantilever is not tangent.  Thus you see a horizontal line representing the x-axis, labeled "0", to indicate zero tracking angle error.  Then you have on the y-axis positive numbers above the x-axis and negative numbers below the x-axis, to indicate that the tracking angle error can go either positive or negative with respect to its vector direction.  Then we audiophiles conflate these data with audio signal distortion.  But I have never seen any experimental proof that the two are linearly correlated.  In the modern era, there is no one who would bother to do that, because we live in the era of BS rules.  In the era from the 50s through most of the 70s, there were reputable audio companies and publications that might have conducted such work.  Shure, for example, published beautiful treatises on cartridge design and performance, in those days.  Early Stereophile did some nice stuff, and so did Audio Magazine.  Then there is/was the Audio Engineering Society.  

Certainly, it makes sense to maintain tangency as much as possible. I don't dispute that that is an attractive idea.  
So, has anyone ever owned, seen, or heard of a test LP that encodes a single frequency test tone from outermost to innermost grooves, on at least one of its two sides?
I've mounted cartridges with alignment done via different tools over the years: dbSystems, WallyTractor, Feickert, UNI-Protractor (best I've used.)  One goal is to get the stylus tip on the null-point(s), another goal is get the cantilever properly aligned with the 'engine'. For moving coil, that could be coil(s) on the end of the cantilever aligned with internal magnet(s). Granted all thus presumes a well made cartridge.

Doing this I played records and listened.  Sometimes I'll put the 'table back on my bench and check the alignment. Sometimes I find I can do a better job aligning the cantilever. Invariably when I do that and listen again I experience better sound. The degree of difference may not be huge but I find it is audible and worth the second alignment.

Null point(s) alignment can change with tracking weight, with VTA adjustment, and with cartridge break-in.  I usually check alignment after, say, 300 hrs of initial use and when adjustment is required I find sometimes sound improves.
tima 
If tracking error was so very important to our listening pleasure; why with all the technical knowledge and manufacturing prowess we now have; are we not all owning linear tracking tonearms on all of our turntables? I would say that there must be far more important factors at play that would lead one to the logical conclusion that the tracking error must not be that critical of a factor in our enjoyment of spinning our records. But that's just my opinion.  
I've recently put a London Decca Maroon (mono) on the end of an Naim Aro, an arm designed around this very premise, which has no provision to adjust overhang having holes rather than slots. The arm board I have was made when I was using a DV17D3, the Maroon put's its stylus 2 to 2.5mm further past the spindle than the DV did so that is my overhang error. After optimising VTA and VTF as best I can by ear I can still hear the music sounds different (and preferable) half way across the disc compared to the beginning so I put the numbers into Vinyl Engine's tracking error calculator assuming 20mm overhang against the recommended 18mm and found the cartridge doesn't actulally cross a null point, but it's not far off half way through the side, the error at the first groove however was ~3 times greater than a correctly aligner cartridge would have. I don't find it unlistenable but I noticed it before I ever checked the alignment with the Feickert, it's enough to make me use up my spare armboard blank to correct it. This system is middling Naim (stageline N/282/Hicap/250) with a pair of Thiel CS1.6.