I first realized the importance of proper azimuth adjustment when someone demonstrated it to me using his Triplanar tonearm. From that point forward, I lusted for a Triplanar. For a very good treatise on azimuth, how to adjust it, why you are adjusting it, what to expect, etc, I recommend a search of the Vinyl Asylum archives for long posts by B Kearns and by V Khomenko (sp?). Those guys are my bible on this subject.
By the way, I own a now antique Signet Cartridge Analyzer which, if you have the right test LP and a Triplanar, makes setting azimuth a breeze, using the direct output of the cartridge itself, which eliminates the possible effects of downstream amplification. But the Signet does not quite have enough input sensitivity for a modern LOMC cartridge output. It needs an antecedent gain stage.
By the way, I own a now antique Signet Cartridge Analyzer which, if you have the right test LP and a Triplanar, makes setting azimuth a breeze, using the direct output of the cartridge itself, which eliminates the possible effects of downstream amplification. But the Signet does not quite have enough input sensitivity for a modern LOMC cartridge output. It needs an antecedent gain stage.