The JACK Quartet were called “superheroes of the new music world” by The Boston Globe, and there could be no more apt description for this endlessly adventurous ensemble. They’ve played pieces completely in the dark, used vibrators on their instruments, performed on a raft in the middle of a lake, and more. For The Angel’s Share, they will play an extraordinary program that follows a musical thread from medieval plainsong through to the present day, drawing sonic similarities from wildly divergent works and echoing the timelessness of the space surrounding them.