Live: Outer Echelon Drone. Emeralds, Union Chapel.

Obscured by a spattering of scaffolding that seems progressively more intent on obscuring the external grandiosity of Islington's Union Chapel as not only months but seasons flutter by, a solemnity customary of any ecclesial construction swamps its interior. Tonight, this particular house of worship has been infiltrated by the Barbican, as their annual Transcender series takes to incontrovertibly resplendent surrounds. Eat Your Own Ears listings replace hymnbooks in the backs of rigid pews; iPhones click impatiently; footsteps pitter and patter from lamentably understocked merch stand, to bar, to backbench. Tonight errs on the side of the spectacular in every sense, for the pioneering sounds engineered by those electronica trailblazers to have been signed, sealed, and delivered by Viennese label Editions Mego are about as far removed from those conventionally expected of the setting as they are, tonight, quintessentially cosmic.

Fennesz, Christian is up first, unassumingly ambling onstage in a cubic leather coat. If Fennesz strives to masquerade his Jazzmaster as anything but a guitar, he certainly succeeds periodically, as his attentively caressed Fender gently weeps one moment, before sounding akin to enraged satanic beast the following. While the manipulated samples to emanate from his MacBook are intermittently as beautifully entangled with his sparse guitar work as a perfectly configured double helix, for the most part he sounds lost within a labyrinth of his own sound synthesis.

As for the Portland trio headlining tonight, anticipation is palpable. Emeralds deliver an instrumental onslaught across their exhaustive, bordering on the excessive back catalogue, yet in raw flesh it's ever more improvisational. If it's a faint start from the experimental wunderkinds, they grow Hulk-like into their show: while guitarist Mark McGuire initially allows melancholic strands of ambient six string to seep from his Stratocaster, by tonight's closing moments he's disposed of plaid shirt, strutting to the fore to wriggle out a series of power stances as his guitar injection becomes increasingly potent. Emeralds' executive architect, John Elliott, similarly becomes almost impossibly adrenalised throughout: headbanging incessantly and irately (explicitly so when sound levels are reprehensibly, if reasonably lower than he'd wildly desire), it's a wonder his braincase remains unscathed. Thus amidst what sounds like a flurry of supernovas exploding in slowmo, seared occasionally by Chris Rea-esque Strat slick, it's Steve Hauschildt stage-centre, the static Prophet synth whiz who takes the edge off the intoxicating vigour that surrounds him, anchoring Union Chapel while it feels as though it could be involuntarily launched heavenward, into frenzied orbit, at any given moment. Instrumental for nigh on the duration, the trio invigorate mind, body, and soul, and there's never any true need for microphonic intervention as the music not so much does the talking as the proverbially intergalactic bellowing so in-your-face you can practically feel globules of sound slap against your cheekbones. They only touch on the sensational full-length of yesteryear, Does It Look Like I'm Here? during a one-song encore, as its eponymous track is blustered through with avidity, and they only air a handful of compositions before they disappear just gone ten yet with sounds this fittingly celestial radiating from the nucleus of N1, all seem to have been helplessly converted.