Peer into the corners of Boards of Canada's catalog to find cases where their sound really turns toward the outer limits, like the ringing tabla and wild flute melodies of “Alpha and Omega” or the surging squalls of feedback in “Seven Forty Seven.” At the opposite end of the spectrum, 1996's “Nlogax” comes across like an electro-funk classic from the early ‘80s, full of retro panache.