Icelandic composer Olafur Arnalds mixes synths with acoustic strings and piano for his fourth solo album, the title track of which showcases pioneering new Stratus software that controls two self-playing, semi-generative player pianos. It’s a dreamlike soundworld that Arnalds juxtaposes with racing minimalist rhythms and pulsing electronic beats. The now-familiar use by post-classical artists of a muffled, close-miked upright piano has never sounded so sweet as it does in “saman,” while hypnotic, fluid textures of “they sink” envelop the velvet sound of a solo cello. Electronica provides the beating heart for the gently oscillating “ypsilon” before the final "nyepi," one of Arnalds’ most introspective, affecting soundscapes.