I don't think you even need high quality equipment or perfect pitch to hear the effects under discussion. I owned a Well Tempered Record Player (belt drive), and now own a Technics SP-15 (direct drive) in the heavy Technics base. I definitely don't have perfect pitch, but I could easily tell the difference between the cheap stretchy 3rd party belt on the WTRP, the outrageously expensive precision ground flat plastic-like OEM belt, and the Technics, with the Technics easily besting the WTRP on all measures of speed stability. If you have better equipment, or ears like Dougdeacon's partner Paul, I'm sure the differences are both more readily apparent and probably really irritating.
Ketchup, as far as mastering goes, here's some interesting reading:
http://www.kabusa.com/1200agon.htm
Of course, the Technics wouldn't be factor for older recordings, which might very well exhibit the effect you postulate. These guys:
http://www.trutone.com/mastering.html
claim the Technics drive motors are way better the the original Neumann. I have no idea whether stylus drag was audible on the old lathes. Your theory has been discussed before here on Audiogon.
Anyway, I'm firmly in the camp that says belt stretch is audible, because I've heard it.
David
Ketchup, as far as mastering goes, here's some interesting reading:
http://www.kabusa.com/1200agon.htm
Of course, the Technics wouldn't be factor for older recordings, which might very well exhibit the effect you postulate. These guys:
http://www.trutone.com/mastering.html
claim the Technics drive motors are way better the the original Neumann. I have no idea whether stylus drag was audible on the old lathes. Your theory has been discussed before here on Audiogon.
Anyway, I'm firmly in the camp that says belt stretch is audible, because I've heard it.
David