Based on my own experience over the years, I'd say the following labels can be generally relied on to have releases that have high quality audio: Dorian; Reference Recordings; Telarc; Erato; Harmonia Mundi; Opus 3; Proprius; BIS; Water Lily; Astree; M-A; Nimbus; Analogue Productions; and Mapleshade. Going back 40+ years, the RCA Living Stereo LP's, as well as the Mercury Living Presence LP's, had superb sound, and many of those old releases have been re-issued (some are coming out again on JVC XRCD).
Among the major classical labels, you can usually also count on Sony, Phillips, London, Decca, and (sometimes) DG to offer good music and good sound. Among jazz labels, you can usually count on getting pretty fair audio quality on: Blue Note; Verve; Soul Note; Black Saint; ECM; Contemporary; and Chesky (not very many genuine jazz releases, but the ones they've done have both good music and good sonics). The other labels that release jazz, such as Atlantic, Columbia, etc., have had mixed success with recordings that have both good music and good audio quality. Among the jazz re-issue labels, I have generally been satisfied-to-pleased with the older recordings done by Contemporary and Riverside.
Among the major classical labels, you can usually also count on Sony, Phillips, London, Decca, and (sometimes) DG to offer good music and good sound. Among jazz labels, you can usually count on getting pretty fair audio quality on: Blue Note; Verve; Soul Note; Black Saint; ECM; Contemporary; and Chesky (not very many genuine jazz releases, but the ones they've done have both good music and good sonics). The other labels that release jazz, such as Atlantic, Columbia, etc., have had mixed success with recordings that have both good music and good audio quality. Among the jazz re-issue labels, I have generally been satisfied-to-pleased with the older recordings done by Contemporary and Riverside.