Veterans of extreme doom bands Burning Witch and Goatsnake, guitarists Stephen O'Malley and Greg Anderson dove even further into the monstrous power of the drone when they combined and formed Sunn O))) in 1998. Cranking up their amps, the duo created a wall-of-riffs sound that was so slow, loud, and distorted that it felt closer to avant-garde noise than metal. With a list of collaborators that includes black metal pioneer Xasthur and art-rock icon Scott Walker, Sunn O))) have evolved in often surprising directions while never straying from the feedback-drenched roar that's become their trademark.