Here in Canada, there are two organizations you have to go through. SOCAN (Society of Composers, Authors and Music Publishers of Canada) and CMRRA (Canadian Music Recording Rights Association). If you are playing music in the lobby, in the auditorium when the audience enters/exits, or during intermission, you need to pay SOCAN. It's a moderate fee, depending on ticket revenue. You're looking at either Tariff 11a or 11b. SOCAN DOES NOT APPLY IF YOU ARE USING RECORDED MUSIC DURING THE PERFORMANCE. (Source: SOCAN rep during the CITT conference this summer.) When using parts of songs during a performance, you're dealing with the CMRRA. In that case, it becomes a recording issue and not a playback issue. By this, I mean CMRRA fees apply to the number of copies of the songs you make beyond 2 copies.
More simply put: if you are using full songs as background, you need to pay SOCAN. If you are using parts of songs that are not background, but an element of the production, you deal with CMRRA.