It’s a Christmas album and Santa has not delivered any instruments, so Pentatonix are here to harmonize and beatbox their way through this festive selection. Old favorites (“Sleigh Ride,” “Winter Wonderland”) are given gleeful and dazzling new a capella arrangements, with a couple of more sober choices (Fleet Foxes’ “White Winter Hymnal,” “Mary, Did You Know?”) for seasonal variety. Their wordless and intricate take on “Dance of the Sugar Plum Fairy” is perhaps the most unexpected gift of them all.