Armed with numerous glittering prizes, the Jamaican-American Jordan Bak is poised to become that rare thing: a star violist. His playlist includes selections by J. S. Bach (originally for violin), our contemporaries Jeffrey Mumford and Joan Tower, and, as it must, Paul Hindemith, one of the viola’s prime champions. This online recital is the penultimate entry in the first season of the Violin Channel’s Vanguard Concerts, which has clocked nearly 2 million views since its launch in mid February. The programs, each about an hour long, were filmed at Merkin Concert Hall on Manhattan’s Upper West Side. LED cyberimagery adds visual interest in the background, but the emphasis is right where it ought to be: on musicians making music. That the artists were compensated (rather than having to busk from home for free) adds to the sheen of the series. The full catalogue remains available indefinitely, at no charge. —M.G.