Between 475 and 100,000 ohms I must confess that the differences I think I
hear in the music are so small they may be imagined. Is this to be
expected or should I run immediately to a good Otolarygologist?
About 30 years ago I worked on developing a box that would allow a person to know what the right loading value for a LOMC cartridge actually was. To this end, I had to pass squarewaves through the cartridge, as the proper loading would be that which prevented 'ringing' a harmonic distortion caused by the fact that the cartridge is an inductor.
To my surprise, I discovered that any LOMC could pass a 20KHz squarewave regardless of loading. The only thing that changed was if the loading value was reduced too much, the output went down.
That was when I realized something else was afoot with loading. Its not the cartridge, its the preamp that is reacting, as described elsewhere in this thread (the loading box concept was thus abandoned).
Some takeaways (all previously covered):
1) If your phono section requires loading to sound right, it is due to an overload margin problem, inherent instability of the circuit, or both.
2) If the circuit is unstable, you will experience more ticks and pops that sound like the LP has a noisy surface.
3) the loading will decrease the compliance of the cartridge, which in turn will reduce its high frequency response. How much is hard to say, but some people (myself included) have heard loading act like a tone control, and this may be part of the reason why, since under normal circumstances, the RF peak that results is usually well outside the audio band unless a MM cartridge is used or the tone arm cable has crazy high capacitance.
