Terry Evans: any of his albums on Audioquest. Also his two albums with partner Bobby King on Rounder Records, a non-audiophile label with many audiophile-sound quality albums in it's catalog. Terry and Bobby served as Ry Cooder's "back up" singers for years, and are both fantastic.
Speaking of Ry, his sideman guitarist (lap steel, mostly) David Lindley's first two albums are very cool, and feature great sound. I have used a 12" 45 of "Mercury Blues" I own as demo material for years.