Perhaps we should add a touch of sympathy – pity even – to the praise any band that has managed to paint their masterpiece is showered with. How exactly are you meant to follow up your definitive statement?

Take the Dirty Projectors as an example. The Brooklyn-based outfit reached a dizzying peak with 2009′s Bitte Orca, which maintained the band’s rulebook-shredding ethos but presented their trademark overwhelming rush of ideas in a more user-friendly package than ever before, resulting in actual emotionally resonant songs as opposed to a bunch of arresting riffs held together by a logic known best to the participants. But the creative triumph presented the Brooklyn-based band centred on guitarist-singer Dave Longstreth with some uneasy questions, namely: what next?

Judging by this highly impressive collaboration with Björk, the answer would appear to be: more brilliance. On paper, the project appears kooky to the extreme. Inspired by vocalist Amber Coffman’s sighting of whales during a trip to Mount Wittenberg in California, and touched with a spirit of marine preservation (the entire proceedings from the original download release last year went to National Geographic Society’s creation of international marine protection areas), the 21-minute mini-album finds Björk and the Dirty Projectors vocal team take on the role of whales and whale-watchers.

But don’t let the odd concept, or the album’s brevity, put you off. After all, here’s a band who spent the first half of the last decade as unstoppably prolific champions of outlandish projects, including a ‘glitch opera’ about Eagles drummer Don Henley and, on 2007′s Rise Above, a deconstructed tribute album to a Black Flag record, based entirely on Longstreth’s distant memory on what the original might sound like. But whereas the earlier oddities provided catnip for the chin-stroking constituency whilst leaving many average art-rock enthusiasts scratching their heads in utter bafflement, Mount Wittenberg Orca is an engaging, deeply felt and often startlingly beautiful record that packs in more substance to its brief running time than most acts manage across hour-long endurance test albums.

Bitte Orca relished in showcasing Longstreth’s considerable guitar heroics, letting loose lightning-speed runs resembling a kora one moment, riffing hard like Jimmy Page with one foot on the monitor the next. Mount Wittenberg Orca is all about the voices. The fiendishly complicated but elementarily muscular beats are also absent. In fact, it takes several listens before you even notice the additional elements – Nat Baldwin’s meaty bass and the odd glimpse of guitar – grinding away behind the vocal fireworks. Both Björk and Longstreth are on fine form: the latter’s unconventional phrasing is let loose to an extent that it takes ages to spot he’s actually crooning a love song – a superbly lovely one at that – on ‘When the World Comes to an End’, one of the highlights. As strong as the lead singers are, however, the biggest round of applause must go to Coffman, Angel Deradoorian and Haley Dekle whose wordless vocals fill in the gaps where instruments would normally step in, see-sawing like a human string section on the rousing ‘On and Ever Onwards’, cooing gently like a particularly soothing lullaby on ‘Sharing Orb’ and hogging the spotlight on ‘Beautiful Mother’, a disorientating tour de force of delicately intertwined vocals lines racing up down the scales.

Add to this the fact that the tunes are uniformly excellent, straighter than in the past but still full of compelling depths (with a bit of meat on its bones, ‘No Embrace’ could’ve been one of Bitte Orca‘s peaks), and it’s obvious the Dirty Projectors’ creative powder remains dry. The release of the band’s next “proper” album – tipped to pop out next year – can’t come soon enough.