I agree with what Ice said, in my opinion, RP, which is similar to literature is not good when paired with music. The music distracts the reader from the text and makes it harder to imagine and materialise the story in the head. Often the music can even contradict, as some people get a slightly different vibe from the same tune.
So, I personally won't include music in my IC posts, and probably won't listen to music in other posts, but I do think one of the places music can add to is in an SU, as the character favorite song, or theme song, etc... and maybe in the "Arc/Chapter" posts where there is a shift in the RP, then music might act like an opening, or ending theme.