I did that test back in 1973!
For the holidays, my parents saw that I was absolutely glued to a 9v pocket transistor radio, and I got an upgrade to a nice single-speaker Panasonic radio / cassette. (stereo headphone out luckily)
They admitted later in life that they just picked up some random cassettes and I got these two:
Switched-On-Bach / Wendy Carlos
en.wikipedia.org
Black Sabbath / Black Sabbath
en.wikipedia.org
I wore them BOTH out. Maybe this is why I'm so messed up sonically - in a good way!
Somehow after this, listening to Tony Orlando and Dawn wasn't fulfilling enough...