And we were getting along so well.

Tim, I think it is all important, right down to the microphones and their placement. I know you have heard (and may own) a copy of that Shelby Lynne confection, "Just a Little Lovin'." I can hear some effects on her voice that sound to me (pure speculation) like limitations of the microphone, that give her voice a hooded sound. (It's been a while since I've listened to the record so I'd have to go back and play it to identify precisely where).
But, and this may be more a function/limitation of vinyl, there are HUGE sonic differences in different masterings of the same record. And, like Myles, I've typically found the best sound in the early pressings where the thing was mastered. Perhaps in the case of older recordings it is the result of being the closest to the original mixdown, rather than a later generation copy, even if these other masterings were done roughly at the same time as the original. I don't think the differences have been blown out of proportion, at least in the case of old vinyl- but, I will grant you, it may be more of a case of other and later masterings screwing up the sound than any 'magic' in the original.