TOD:
It's hard to say what my first exposure to classical music was unless it was the William Tell Overture while watching "The Lone Ranger" on Saturday mornings in the 1950s.
Of course, TV featured classical music in a lot of newscasts, etc., but I never knew what I was hearing.
My first recording was of some Strauss waltzes. My mom picked up a bunch of cheap recordings on LP after I got my first hi-fi. I was fascinated by them, but had no way of measuring the performances.
In band in high school, the first classical music we performed that grabbed my attention was a movement from Wagner's "Die Meistersinger von Nurnberg". It was complicated, complex and thrilling even when heard through "band ears".
As an adult, I have to say there are two recordings that were my first major loves of classical music: Sir Edward Elgar's "Enigma Variations" (and, of course, his "Pomp and Circumstance" was something I had heard many times as a youngster attending and playing in the band for graudations); and Puccini's "Turandot", with Joan Sutherland and Luciano Pavarotti. I had purchased the opera on LP (a boxed set) in the exchange in Vicenza, Italy. Took it home, grilled a steak on a hibachi on my balcony, opened a bottle of wine and listened to the entire recording. It took (and still takes) my breath away,
That was the beginning, but no end is in sight.