A portion of Pat Metheny’s concert at Muriel Kauffman Theatre two weeks ago was dedicated to unaccompanied wistful meditations. Few musicians can match the breathtaking beauty of guitarist’s artistry when he works in a hushed contemplative mode. Dream Box, Metheny’s new album, consists of 56 minutes of transcendent serenity. He offers insights into the set in a brief video. Free from the cloying treacle that often spoils like-minded efforts by lesser artists, Dream Box is an ideal companion for tranquil introspection.