This is definetly the one tool I'd love for 2K10. I really hope someone has started work on it, cause I'm not that technically savvy to even know where to start.
When such an editor is released I am going to start a arena music patch updating the stadium music to feature songs that are played in real arenas.
Also, I'm thinking about putting some filter on it so that it really sounds like it's playing in the arena and not just music playing through the speakers.