If you are in for an event dealing with music connected to Easter, and the mystique around the Easter celebration, the Misteria Paschalia Festival in Krakow is the thing to check out. Between April 2nd and 9th this festival is arranged in Krakow, and you can read more about it on the official homepage of the festival. The Misteria Paschalia Festival official homepage can be found at: http://www.misteriapaschalia.com/
Ps: the homepage is not yet updated with information about the festival in 2012 (January 5th, 2012)