After the release of the epic, expansive Monoliths & Dimensions in 2009, Sunn O))) released a string of collaborations — with Nurse With Wound, with Ulver, with Scott Walker — and began a vast live archive documenting dozens of shows from every era of their existence. Then, in 2015, they dropped Kannon, their first formal studio release as just themselves in six years. The core duo of guitarists Greg Anderson and Stephen O’Malley were augmented by their usual pool of collaborators, including vocalist Attila Csihar, guitarist Oren Ambarchi, Randal Dunn, Steve Moore and Rex Ritter on keyboards, and Brad Mowen (formerly of O’Malley’s band Burning Witch) on concert percussion. Kannon is a concise album, just three tracks in 33 minutes, and there are no musical surprises. But if you listen carefully, they’re ringing subtle changes on their core sound; O’Malley’s guitar shifts from ultra-heavy doom to Fushitsusha-esque storm clouds to metallic clanging, and Csihar’s vocals become quite liturgical on the second track (the album functions as a suite, almost as ritual music). Give it your attention and it will reward your focus.