The Chamber Orchestra of the Triangle and the Concert Singers of Cary join forces for two concerts this weekend, offering a contemporary opera and a classic choral work in both performances. Samuel Barber’s 1959 “A Hand of Bridge” is a short one-act in which four players reveal their inner frustrations, and Franz Schubert’s 1822 Mass No. 5 is a deeply moving, lyrical piece for soloists and chorus. $20. Saturday: Cary Arts Center, 7:30 p.m. 919-469-4069; concertsingers.org. Sunday: Carolina Theatre, Durham, 3 p.m. 919-360-3382; www.thecot.org.