In this article on an interactive music system, the author says, “I would claim that we have passed the musical Turing test.”
Since human played music has been pushed so far in every direction (minimalism, serialism, free jazz, etc.) I would think the only thing a musical Turing test could test would be whether something is humanly possible to play on a given instrument. E.g., 256th notes on a trumpet would be tough for a human but cake for a computer.