Over the 14 years that Greg Anderson and Stephen O'Malley have run Sunn O))), the pair have eagerly tested threshold after threshold. The Seattle-born drone metal project's songs are long — the shortest track on 2009 LP Monoliths & Dimensions is 9 minutes, 42 seconds. The music consists of elongated, sometimes agonizing guitar notes accompanied by minimal melody. And it is delivered in person via ear-annihilating stacks of amplifiers. In an August interview, Anderson said that the duo don't think of their music as "pure entertainment," but rather as something that evokes a listener's reaction — "not anything specific, just a reaction to it rather than ambivalence." Even Sunn O)))'s name has a layer of inaccessibility to it: A tribute to amp brand Sunn, the "O)))" goes unspoken, and nods to both the brand's insignia and the band's overwhelming decibel levels.