As roberjerman suggests, a direct-to-disk LP. Once you've heard one, everything else sounds veiled, compressed, and lifeless. Sheffield made a bunch of them, both Pop and Classical. There are other d-2-d labels, but the Sheffields are easier to find and cheaper to buy. You may not like the music much, but for sound they are unmatched.
For albums made with a recorder, the releases on the Water Lily label possess instrumental timbres as natural and sonics as transparent as have ever been recorded onto tape. I suggest "A Meeting By The River", acoustic guitar by Ry Cooder.