I like this poster that Milton Glaser created for the Philadelphia Orchestra. I like how he created the P from a f-hole and a abstract design music score. 

I had a similar design challenge recently when I had to create a logo for the Pennsylvania Jazz Collective. I realized that the P and the J could be found in the treble clef, so I created a stylize treble clef as the logo....I am currently still working on drafts of the logo for the client, but here is part of it.