J.S.Bach "The Goldberg Variations" [ Glenn Gould ] (1955)

Glenn Gould's interpretation might be the most famous, and is worth a listen. [VIDEO] (1955) [LINK] (1981)

Not the OP but happy to help! Since you already like Bach, start by exploring his work! Let's start with the Goldberg Variations, which are 30 variations on a theme set for the keyboard. Glenn Gould's 1955 recording is perhaps the best known recording of this work: [VIDEO] I also greatly enjoy Andras Schiff's interpretations of Bach: [LINK] For opera, I suggest starting with the Magic Flute by Mozart. There are so many good recording to choose from but why not watch the thing? It's meant to be a visual/audio format, after all! I suggest this recording of the Metropolitan Opera - it's what got me hooked on operas many years ago: [LINK] If you like Maria Callas, you'll love Italian operas. Why not start with the classic, La Traviata? I can't find any of Callas's performances online (aside from clips), but you may like this performance with Anna Netrebko: [LINK] Finally, a note on where/how to listen to classical music. I find Youtube to be an incredible tool for listening and for discovery. It's not necessary to dig back to vinyl or 8-track to listen to great performances - they've been remastered for CDs and lossless media. But ultimately you want to listen to it in person. I'll never forget seeing my first opera in person (The Flying Dutchman). Or the time I scored orchestra seats for Sibelius's 4th symphony. Until the performances return, you might want to buy a ticket to an online performance on DG Premium, which is Deutsche Grammophon's streaming service: [LINK] Good luck

You can't stand this? [VIDEO] I don't think you need to appreciate structure to find this at least somewhat interesting or telling of something, even if nothing specific.