Wow… that is some in depth knowledge on a pretty esoteric subject. Also, really interesting. Thank you for your post. It is typical for any label to have variable sound quality. Although some are better than others. I do remember one or two having high levels of surface noise. I’ll have to look at them more carefully.
Also, you reminded me of different equalization curves… which my phono stage has as an option. I’ll have to be careful to use them.
Thank you for the info.