Music review: iamamiwhoami, Electric Brixton, London

They're described as a “multimedia entity”, a “internet phenomenon” - but please don't stop reading. Yes, the name iamamiwhoami is annoying, and yes, they are best known for their lengthy, mystery, teaser-trailer, viral internet video campaign – more words to make the heart sink, unless you're a hipper-than-thou 17-year-old.

But I encountered iamamiwhoami through their first full-length record, kin, which may be the old-fashioned way, but it generally works. The Swedish collective's combination of icy, ethereal vocals, crisp electronic beats and slow-build but ear-wormy, pulsating melodies proved winning.

They've just released bounty – although it's an album of already-on-the-internet songs, stretching back to 2009, so no wonder everyone seems familiar with most of the music tonight. Iamamiwhoami have a following, it seems: the audience is collection of right rarities – more imaginative side-shaving of heads than you can shake an eccentric piercing at – but they're pleasingly keen.

For a group who've made so much of video art, iamamiwhoami have a traditional show. There's a big cube, which fills with smoke and lights, and there's a lot of strobe, but elaborate visuals are eschewed in favour of the time honoured electronic-music-goes-on-tour set-up: a few guys hunch and twiddle over synths, keyboards and computers while a quirky lady sings and flails about.

Frontwoman Jonna Lee sure fits the bill; long blonde hair as pale as her chilly tones, in a skintight black bodysuit, she performs an apparent mix of Seventies-style interpretative dance and semaphore. Her voice is capable of very high pitched purity, but largely warped and spun with effects; lyrics are incomprehensible, but the sound has its own airy beauty. There are points - as on 't' – when she's swoopingly Kate Bush-like, and wearing a crown made of tin foil, then a shaggy coat that closely resembles a Wensleydale sheep (familiar from their music vids), she matches her for loopy dance moves and sartorial choices too.

iamamiwhoami are at their best when they deliver a bit of swagger, some serious stomp – as on the siren-urgent 'In Due Order', or 'Goods', where Lee gets the audience disco-dancing to the Eighties synth line. But while they frequently nail a combo of fragile, dreamy vocals, primordial sludgy bass and robotic electro-pop, the overall effect can, after a time, become curiously flattened and samey. It might fare better danced to at 2am on a Saturday morning than nodded to on a schoolnight. Or maybe even watched on YouTube.