“On our earlier recordings, we experimented with low tones that only dogs can hear”: Sunn O))) on the challenge of working with 130 guitar tracks and why their live shows are like jumping into a frozen lake

Greg Anderson and Stephen O'Malley of Sunn O))) wear cowls as they perform live in front of banks of high-powered tube amps.

10 albums since their formation in Seattle in 1998, Sunn O))) have built an intimidating and intellectually rigorous catalog of music based on subterranean riffing, currently in trouser-flapping drop-A tuning.

A wide range of alternative musicians have performed with them over the years, including Joker soundtrack composer Hildur Guðnadóttir, Japanese experimentalists Boris, singer Attila Csihar of black metal ghouls Mayhem and the avant-garde songwriter Scott Walker, whose collaborative 2014 album, Soused, was one of many high points of the duo’s prolific career so far.