I've recently been trying to get AY/YM music playing on the SID chip. (for my own amusement) Using data from the old YM format by Leonard/Oxygene, I'm streaming compressed register output in real-time to give a fairly ok sounding simulation of the AY.
Here are some examples of Atari ST music. My pre-processor does frequency and volume conversion, and using the Exomizer compressor most tracks export out to a 4-40kb size depending on complexity. (rather than song length)
Playing Scavenger's "DBA 6" intro track. Rudimentary buzzer and sid support. Oh, if you're wondering the visuals are the decrunch buffer. :) There are some mistakes with the buzzer but it'd probably a lot more work than I want to put in to get something more accurate.