The Crossing is a relatively young American ensemble, about 35 singers strong, that has gained unusually wide critical acclaim while specializing in contemporary music and bringing a broad variety of new music to the repertory via commissions. The choir was founded in 2005 by a group of friends who included veteran choral director Donald Nally, who had served as artistic director of the Choral Arts Society of Philadelphia and as chorus master of the Lyric Opera of Chicago. (A co-founder, Jeffrey Dinsmore, died suddenly during a rehearsal in 2014.) The new group quickly gained ...