The first Classical I heard was on TV when I was a teenager (I didn’t come from a musical family). Being a modern, "raised-on-rock" kinda guy, I found it SO boring: slow, plodding tempi, orchestras with huge ranks of stringed instruments played with an extreme degree of vibrato, all sweet and cloying (think Montovani ;-) . Bla! Those adjectives I now associate with the overly-Romanticized performances of what can and should be bracing, energetic music. That was done to Beethoven and Mozart by the 20th Century Symphony Orchestra, and it imo emasculated their music.
Then a couple of things happened; I heard the debut albums of Van Dyke Parks and Randy Newman, both of which featured orchestration. And, I got a job at the best record store in San Jose, Discount Records (owned by CBS), which had a complete Classical inventory and clerks who knew the music, a couple of them music majors at nearby San Jose State (now University of California San Jose).
Van Dyke Parks had collaborated with Brian Wilson on the ill-fated Smile album, with which I was obsessed. Van’s Song Cycle album was a revelation; if you haven’t heard it, remedy that situation! On that album Van included a song by some guy named Randy Newman, so when his first album came I had to hear it. And I loved it.
I asked the Discount Records Classical clerks for advice on music less "easy-listening" than that which I had heard, and they steered me to Stravinsky and the other 20th Century composers, even Penderecki ;-) .
Next came recording with a songwriter who was a music major at The University of California Riverside. He helped me navigate my way into Mozart, and finally to the source of all: J.S. Bach. This songwriter (who died at a young age, the victim of his terrible diet) used his knowledge of composition to write his songs, just as does Brian Wilson. See, that’s "the problem" I have with guys like Keith Emerson/ELP and other Progressive bands; they wear their "Classically-trained" badges on their sleeves, but the songs they write exhibit no evidence of compositional wisdom.