Yeah, it was the soundtrack CD that was provided in high quality.
Unfortunately no high-quality copies of the music not on the CD exist. The files in the game itself are relatively low quality, and very clearly inferior to the pristine quality of the soundtrack CD. As all rips are at least
as bad quality as the in-game files, you're never going to find quality on par with the soundtrack CD.
Another reason why I said I'd love a Grim Fandango remaster