More? REALLY want - to KNOW just - how it ends ?
It is a truckload of money ( I will most likely not posess any time soon, let alone decide to spend on ) : http://www.dnaudio.com/Tan.htm
There is even a Reference/Statement/Signature/Whatever version, that for an appropriate fee ( a couple of Ks ) adds REMOTE CONTROL for the VTA adjustment on the fly.
But it starts much more benign, like Technics SL 1200/1210 - if the VTA adjustment is functioning properly, it can be operated while playing a record and a lone listener might be able to listen to the results on, how appropriately for head-fi, headphones. But you have to be careful not to demage your record or stylus - or worse.
Guess I have reached a half way closer to you have guessed by now which extreme : Eminent Technology ET2, a "poor cousin" to the above Sweden arm, which also allows for VTA on the fly ( no VTA remote for all the money in this world available ) - being the only arm I know of that has VTA adjustment that travels in an arc, not disrupting the lateral geometry as any other, above mentioned arm included, does with adjustment to VTA.
Should I ever bring myself to have each and every record in my collection listened to and dialed in for the best sound with THAT record, painstakingly noting the reading off VTA dial on the ET2 ( I WOULD add digital VTA caliper in such case ) , my worst possible nightmare would be then having to change a cartridge and/or stylus - necessitating addendum to the previous setting by noting the required difference established between the carts. Add to this any mat change - things begin to get a bit out of hand about here and one may well end up in an institution that is not exactly high on the desirability list - for meticulously observing ALL the rules regarding analog vinyl.
Just how much height difference with a normal 9 inch effective lenght pick up arm at the bearing side IS audible?
0.07 mm .
That is why you will most likely find digital calipers in close proximity to my turntable(s).
There are incomparably more "sane" guys like Rega that tell you as long as your cart points in about the right direction it should all be OK -forget about VTA, azimuth, etc, just play music. Those Regas out there would be FAR better sounding if at least some of the adjustments they deliberately leave out with the excuse of better rigidity etc claims would somehow someday find their way into any new Rega product(s) - which are otherwise very good.
Like with everything in life, a sound compromise is in order - but then please do not try to use the latest greatest sharpest stylus tip on something that does not allow for VTA adjustment...and then bitching it sounds like crap while costing the wrong end of $$$.