Around about 1998, I was talking to my electronic music teacher and ethused about the day that would come when we could put, say, everything Mozart ever did on a single cube, holding my fingers up in the air separated by about an inch. "You know, not everything Mozart did was great." "No, I get it, I just mean him as someone who put out a lot of stuff. Everything the Beatles ever did would work, too."
Silly me. I thought it would take a cube.
For $3, you can get the Big Mozart Box and for another $1, the complete Mozart symphonies. This clocks in at approximately 2.6GB of reasonable quality MP3s. (Not the bestest possible, but certainly pretty good.) It's not everything he did, I don't think, so let's call it 4GB total. That's a mere 1/32nd of a 128GB SD card, which is very much an areal storage device and not a cubic one.
In other news, if you've been inclined to buff your classical music collection, it turns out to be really cheap to just buy the MP3s, even if you've already got Amazon prime.