I'll throw out a few of my favorite recordings:
Beethoven, late quartets, Yale Quartet on LP, Cleveland Quartet on CD.
Debussy, Walter Gieseking (both vinyl and CD). A steal on one EMI 4-CD reissue. The sound is ASTONISHING mono.
Beethoven 6, Bruno Walter/Columbia SO, on SACD, LP, and, yes Cassette
Britten, Peter Grimes, Britten conducting
Copland, Appalachian Spring, Copland conducting
Copland, Fanfare for the Common Man, Bernstein
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VPI / JMW arm, with Dynavector 20 (also Technics 1200mkII), Luxman 505u integrated, Marantz 8004 SACD/CD, TAD/Pioneer S-2EX speakers, GIK room treatments