if the band has a scheduled performance, you can ask if you can attend that event to watch them live. there is nothing to worry in this kind of things since many couples have already done this one in the past. if you plan to do this one then you have to make sure that you are doing this not because you want to take advantage of other couple’s wedding celebration but to assess the performance of the band.
one of the things that most couples look forward to during their wedding reception is for the bands to play their favorite song or a special song they have for their partner. 