Both Alva Noto and Thomas Knak have well-documented predilections toward breathable, open-aired soundscapes, so [bad word] as no surprise that Opto Files -- their joint collaboration -- is a meditative, vapourous swirl. With only a few elements ever occupying the stereo stage at one time, it's not difficult to traceroute their individual contributions -- Noto's are the emery paper skiffles and velcroed rhythms, Knak's are the single-motif organ melodies and translucent hums. Each of the four tracks on Opto Files remains faithful to this blueprint while conjuring a distinct mood of its own. "Opto File 1" is a warm midevening balm of gently unravelling synth pads and agitated static, "Opto File 2" an industrial phone line interference piece played on a broken switchboard, "Opto File 3" a glitch-tickled lullaby with a slumberous organ, and "Opto File 4" is a motionless, barely there drone piece that empties itself out to a close. Those in search of either more immersive glitch or more melodic electronic might ultimately be better off consulting Noto's and Knak's solo discographies respectively, but as a passive ambient excursion, Opto Files does its duty. -- Allmusic