Digging in the crawlspace, I found a shoebox full of tapes, including tapes of myself playing in my high school days. With more digging, I was able to put together enough technology to pull the sound off. This tape was made in 1987, when I was a senior, as an audition tape for an honor band. So I was in shape, practiced up, and performing under pressure for a competition: not a bad snapshot of where I was then. The piece is selections from the Hummel concerto: basically the first page of all three movements. There were a number of takes of the first movement on the tape, this was the master I guess, and I pulled off only the last. Not sure which take we ended up using for the submission, they all had goofs of varying severity. Maybe I quit because I sucked. I should try recording these selections again now, for comparison.
Added: here's a YouTube video of the beginning passage, being played by Valeri Popov. In case you're wondering what it's supposed to sound like.