usage of copyrighted music at startup convention?

reproduction as well as public performance are one of the exclusive rights owners are granted by statute. What an individual can get away with is less so with firms who should know their business law. If someone dobs them in, expect a few legal raps across knuckles unless a mea culpa followed by licensing follows. Even the chinese video ... err ... replay sites had to toe the line, or at least the highly visible ones.