It’s the Discworld series by Terry Pratchett with original narrators (Stephen Briggs and Nigel Planer).
Audible has been replacing them with new narrators, and they switch narrators several times every few chapters in each book. There’s still some of the originals around on audible but they’re slowly replacing them one at a time. It was difficult to find a complete collection and all in good quality from torrent sites before.
I’ve ripped them directly from the CDs so it’s (mostly) great quality with the exception of a few that were converted from older tapes. And all the extras like the science of discworld books and a collection of short stories by Pratchett too.