Our ordinance used to say you couldn't exceed so many decibels after 10 pm, but now it says something about making disruptive or unusual noises after 10 pm. An ex-friend used to jam late at night and learned the wording allowed him to do it if they didn't play too loudly. He's an idiot either way.
There was an article about Will Lee of The Letterman Show having an apartment in NYC that had a room built within a room so he could play live music at any time. There is specific code written in NYC about playing live music blah-blah-blah.