CANTUS, the nine-member a cappella male ensemble regarded as one of America's finest, will astound you with their touching concert recalling the remarkable World War I truce between Allied Forces and German soldiers. Out of the violence of the Great War's trenches comes a silence, then a song as a young German soldier steps into no man's land singing "Stille Nacht." Thus begins an extraordinary night of camaraderie, music and peace told touchingly through actual letters written by soldiers and new arrangements of European carols and war songs. The Washington Post hails the ensemble's sound as having both "exalting finesse" and "expressive power" and refers to their music-making as "spontaneous grace."