It’s a multigenerational Christmas With the Bach Choir, when the renowned chorus takes to the stage for its annual concert this Sunday afternoon (December 7) at the Orpheum. Under music director Leslie Dala, the choir performs with its child and youth ensembles—400 voices in all, plus more if you count a few audience sing-alongs of such holiday hits as “Hark! The Herald Angels Sing”. Amid the repertoire is a newly commissioned work written by former Vancouver Bach Children’s Chorus and Youth Choirs conductor Kathleen Allan, as well as traditional carols and transcendent seasonal choral works.