You'd need a notch filter. Otherwise, background groove noise will swamp the test tone and make the readings highly unreliable. However, IME doing it this way is a waste of time.
I rough in azimuth by eye (make the stylus riding in a the groove appear perfectly vertical), then fine tune by listening. It's easy once you know what to listen for and it trains your ears. Fussing with voltmeters (I've done it) and other gadgets only trains your obsessiveness. :-)
