From his early years in the boundary-breaking downtown New York scene to his fruitful ongoing tenure in Seattle, pianist and composer Wayne Horvitz has led a host of ensembles in varied idioms, but very rarely in trio form. An opportunity came to hide away for a week in a Montana studio with two Seattle colleagues (bassist Geoff Harper and drummer Eric Eagle), which resulted in The Snowghost Sessions. At the core is a straightforward acoustic sound with piano, upright bass, and restrained drums, full of the dark, cloudy harmony and subtle dissonance that is recognizably Horvitz’s language. But the music departs at every turn: Horvitz’s use of keyboards and live electronics is, alternately, gently atmospheric (“Yukio and Nao’s Duet”) or radically disruptive (“Imb”). The textures might emulate the metallic twinge of guitar (“Apart from You #2”) or enhance the legato character of a delicate melody (“55 6 (7) Variations”). The gospel flavor of the organ on “Northampton” adds yet another stylistic reference point.