Cracked Refraction ties its complex knots with infectious vigor and a predilection for playfulness. Wrack’s melodies are slithering and serpentine, and the music is built of smaller segments assembled in what can seem a slapdash manner, with all sorts of jutting ends and unexpected collisions. What Bruckmann’s done, though, is intentional, placing his players on different planes, with straight lines failing to meet, runs of notes ricocheting at impossible angles, and expected avenues folding in …