Although claiming that Black One is the darkest Sunn 0))) album yet may be a little overzealous on their label's part (unless, of course, its meant as a not-so-subtle play on most recent predecessors White1 and 2), there's certainly a good chance that it's their most diverse.
Whether that's a simple case of there being more and shorter songs present (all of seven, and only shorter by these guys' standards, mind you), or an unprecedented volume of outside collaborators (mostly underground black metal buddies lending their vocals), Black One experiments with a number of new tricks to go with the by now expected ultra-droning aspects of Sunn 0)))'s sound.
For example, both "Orthodox Caveman" and "Cry for the Weeper" drink from the same old, Earth-derived dead-water pool that inspired Greg Anderson and Stephen O'Malley to start melting their amps in tribute to begin with; while the improbably brief "It Took the Night to Believe" (featuring blood-curdling shrieks and croaks by Wrest) may well be Sunn 0)))'s most unapologetically black metal moment ever, taking a page from Burzum's bloody book with its spooky loop of buzz-picked guitar melodies to go with a reliably subterranean foundation.
Keeping with the black metal mindset, the pair then proceed to deconstruct Immortal's "Cursed Realms (Of the Winterdemons)" into a barely recognizable primordial soup of tonal thrumming, before calling Xasthur's Malefic down to the basement to supply additional screams for the splendidly named "Candlegoat" and megalithic closer, "Báthory Erzsébet." (For the latter, in fact, he was supposedly locked inside a coffin, microphone and all, so as to inspire a suitably suffocating feeling of horror -- proving that extreme sounds sometimes truly do demand extreme measures.) In other words, Black One is a cautious but unquestionable departure from Sunn 0)))'s pre-established m.o., and arguably their most accessible effort to date, in the bargain.
But even though there'll always be those purists looking for a bone to pick, its difficult to imagine too many original fans not embracing these still remarkably blackened sounds.