Classical is one genre where digital recording is pretty indisputably better. It's not just the technological improvements in the late '70s; the Itzhak Perlman (digital) Beethoven concerto sounds much better than his (analogue) Brahms concerto, and they're only separated by a year or two.
There were great and rapid advances in recording technology in the 1950s and early '60s. By the late '50s some artists who had already cut an LP recording re-recorded them with the latest technology, and then they and others made a third recording in the new stereo format. Early-to-mid '50s classical recordings are pretty scarce and are reissued only for exceptional merit: the earliest you'll generally find go back to the earliest stereo and no further.
Mercury Living Presence discs in particular sound ahead of their time.