Gritingrooves, various cartridges are more and less sensitive to changes in VTA. Grados typically are pretty tolerant of VTA and typically don't change much sonically with small changes in VTA (unlike some other cartridges). Trust what your ears are telling you about the best setting. Many Grado models seem to sound best with a slightly lowered VTA (the arm slightly down at the rear). As you comment, give priority to the cartridge manufacturer's recommendations because of variances in alignment of the cartridge body from manufacturer to manufacturer.
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