Although guitarists Kurt Rosenwinkel and Tim Motzer share a Philadelphia connection, they met abroad while Motzer and drummer Gintas Janusonis were working as a duo, accompanying poet Ursula Rucker. Rosenwinkel heard enticing possibilities and later joined forces with the duo for a freely improvising project named after a beginner amplifier. Each of their distinctive guitar voices is very present—Motzer more trebly and acoustic-electric, Rosenwinkel more mysterious and flowing—but there’s also extensive effects and electro-haze, creating a deeply meditative and sonically inventive space on these tracks drawn from live recordings in six cities. The band’s practice is to start from nothing and build something, every time out, no preparation. But Rosenwinkel’s otherworldly harmonies, Motzer’s refreshingly edgy timbres, and Janusonis’ abstract grooves have a way of spilling out beautifully onto that blank slate. “At the Gates,” once it kicks into surging tempo via Janusonis, opens the floodgates for a Rosenwinkel solo that has to rank among his personal best.