Cartridge azimuth adjustment using a voltmeter and a test lp


Hello all,
I know that azimuth adjustment comes up often as do the various methods to get it right- or close to right.  I have been doing a lot of reading on the subject and I realize that using a voltmeter with a test lp has its flaws vs using other techniques that use sophisticated instruments and magnification to physically determine if the stylus is perpendicular to the record surface.  Nonetheless I would like try using a voltmeter to see how this compares to how I have the cartridge currently set up- but I have a question:
The generally accepted method is to use the amplifier output terminal to measure the voltage output of the test lp- but would it be a problem to measure the voltage at the speaker terminals?  Even with the interaction of the speaker cables the voltage variation at the amp terminal vs the speaker terminal should be very minor.  But I have seen in some posts that some suggest it is better (or necessary) to measure at the amp terminals.  Why?
Arguably, if cable and other circuit interference were such an issue then it would make more sense to measure the voltage at the tonearm terminal for the phono cables, assuming the voltmeter has the necessary range to measure such a low voltage output.

The reason I ask is that reaching behind my amps, pass labs xa60.5 mono's, would be a real pain and if the measurement has to be taken at the amp output I would like to understand why.

Many thanks for your advice.

System: Thiel 3.7's, or Magico S1 mk1,  Pass Labs xa60.5 mono's, Vinnie Rossi LIO preamp (slagle AVC passive mode) or Prima Luna Dialogue Premium preamp, Moon 280 Dac, PS Audio Stellar phono, VPI Aries 1 turntable/JMW 10 tonearm with Lyra Delos cartridge, Nordost Heimdall 2 cabling.
pgastone
@sdrsdrsdr 
Yes it's zenith.  I had become used to referring to it as horizontal tracking angle.  Of course it is setting that (HTA/zenith) and overhang at the same time.

I am completely indifferent as to what affects a Fozgometer.  I think using devices like $400.and even more expensive protractors and big buck microscopes and meters is ridiculous and represents analog insecurity at its worst.  Your ears will do the job just fine.

@mrubey,
Why do you think you have to say the same thing over and over.  And why do you have to believe that your monaural way is the best way---and the only way.  I have achieved the optimum (for me) azimuth setting by aural observation of sound stage.  Maximum sound stage is exactly what I aim for and I find it best to approach it directly.  
@melm   yes. I would agree that setting by ear is probably best. Not everyone is capable of this though and that is why  the tools are necessary. After many years of being into vinyl I’m starting to learn to set by ear. I still have a hard time with this, and I still find that the majority out there are not capable of this. I’m not necessarily referring to any of the forum contributors. Even using expensive  protractors and meters many don’t have the skills to do proper setup. There was just someone asking recently on this forum looking for someone to do setup for them.  The tools are good aids to help people  to start doing it themselves.
Thank you cleeds. Well said and right on the nose. Another problem for the meter people is that the output of the channels is not exactly the same leading to stylus miss alignment. I'm all for the lowest levels of cross talk but not at the sake of record wear but like I said before most modern cartridges particularly the ones with irreplaceable styli are very well made. A perpendicular stylus = lowest cross talk.
Post removed