You should spend some time searching the Steve Hoffman forum; once you have read posts there for a while you learn who knows these records and who is just posting what they have. For what it is worth I think my early Santana's are KC prefix; on Rumors there is a bunch of stuff about "f_" and whether there is a scream along with some re-do's but I am not much of a post Peter Green FMac fan so I have never spent much time culling through all my copies of Rumors or self-titled. Cannot help you at all on AC-DC. I will tell you that once you get into the realm of so-called "best" pressings you are comparing differences that may or may not make one appeal more to you. The consequence is, that with rare exceptions, on many of these multi-million selling records, you can buy multiple copies- most are reasonable and make your own choice. For Hotel California I probably have a dozen different copies but rarely listen to the album. On the early Eagles, I like those white label asylums (they aren't promos it was just the early label art). Some of those may be Monarchs but I am on the road right now so I don't want to rely on memory. The great posts on Hoffman regarding some of this stuff are older and involve some extensive comparisons. Since this is well tilled ground I suggest you search extensively there first rather than post a query since you will probably be told as much. And again, apart from sonic preferences not all the posts or threads on the subject should be considered the last word. Fwiw, if the Peter Green era interests you, there is an old UK CBS compilation that is terrific. It isn't terribly expensive but the shipping from a UK vendor may add to the cost. Good luck and have fun. I have a bunch of stuff I am currently writing but it is about more obscure records including some of the old Vertigo Swirls. I can update you when that sees print.