The Pugnacious Priest was awesome enough to create music from shadow priest DPS. Well, I learned that I don't know how to use garageband very well, so I'm having a hell of a time getting it in. So I did what I usually do in these situations: got frustrated and then got distracted.
I decided to take a crack at a death knight instead. Their rotations make some sense to me. I picked frost because well, it's the best spec. I ended up with five notes: icy touch, plague strike, blood strike, obliterate, and frost strike. Trying to put these onto a piano yielded a semi-listenable sound. Icy touch was a high note, while obliterate was the lowest. I will have to tweak that, perhaps move some spells away from the piano. It did sound kinda neat when I put it on a bass, but that may have just been due to reduced ability to hear it.
As I find more time I'm going to keep working on this. My eventual hope is to have every class-spec combination mapped out more or less on the same scale so that any note would correspond to a spell. Then I want to put them together and see what a raid sounds like. My guess: terrible.