Question - when a disk says "remastered from the original 78s" would that most likely be a needle drop with some cleanup from mastering software? There was no additional information in the packaging.
The only answer I could give: "It depends."
There are a few ways that a 78 could be transferred to digital. This might help clear up the process.
78s were actually cut in wax, not lacquer (or later, copper, as in DMM--Direct Metal Mastering) as we do in the LP era. The wax would then, in essence, be coated with a very fine application of metal, enough layers being applied so it could be handled--this is the "metal master" and at this point, the grooves are inside-out. From there, another set of discs are made ("mothers") from which the stampers (which are, again, inside out) that pressed the actual records we bought.
When records were pressed, the metal parts were often kept. The "mothers" would theoretically be playable, yet, you would not want to damage something that you could produce more stampers from, provided the mothers aren't too worn out to use. So, in order of the quality (and preferability) of the source, there are three primary ways 78s could be dubbed to digital:
1. A digital dub from a 78 could be from the mothers. Or they are sometimes called, "the metal parts." In essence, not an end product. Because they were usually stored somewhere safe, they would have no wear to them, and be relatively clean. They are the closest you could get to the original source. Some play back very cleanly.
2. Demo records were often made on acetate discs (called "acetates"), and acetates were not usually sold to the public: first, they were like a manually-recorded discs, for which only one would exist; and second, acetates do not wear well. So, if someone had found acetates that were pretty much untouched, they would make a great dub.
3. If these two aren't available, then it is entirely possible that a consumer 78 RPM record could be dubbed.
The Rhino Spike Jones set from the 1990s was made from the metal parts and sounds fantastic--most of the time you wouldn't even know they were from disc. (They made a point of doing it this way, as later dubs that RCA made were horrendous, especially the fake stereo anthology LPs they put out of Spike Jones' music. Or IOW, if Spike Jones was murdering the classics, RCA was putting the last nail in the coffin!
)
If dubs are made from metal parts, you may only occasionally hear surface noise--any noise reduction tends to get rid of some noise at the expense of making the rest of the music sound strange. (Once you hear its effects, it's hard to forget.) I have some Perez Prado recordings from the late 40s through the early 50s that in many cases were from 78s, and occasionally you can hear a "swish" each time the disc goes around. These were on the Tumbao Cuban Classics label. Some are rather muffled, and I've heard the same recordings elsewhere that weren't so muffled. So, Tumbao just chose to cut the high frequencies a bit to compensate.
That's it, in a nutshell...