Among the plaudits rained down on Fleet Foxes in recent years, "electifying live performers" seldom figures heavily. There are many things that are immensely cheering about their rise to mainstream fame – and in tonight's audience, the ratio of mainstream record buyer to freak flag-flying acid folk enthusiast is skewed heavily in the former's favour – but the one question that hangs over it is how well their music can translate to the big venues their success demands they play. Their sound is intricate, hushed and intimate: you only have to listen to 40-year-old tapes of Crosby, Stills, Nash and Young angrily shushing stadiums full of fans to know that projecting those qualities to the back of big halls is a perennial problem.
A quick glance at a photo of Fleet Foxes somehow suggests their live performances aren't going to be an electrifying spectacle, and so it proves: there's a moment at the start of Your Protector where not one but two members start playing flutes, but the show struggles to reach that kind of retina-searing level of visual excitement again. But then, it doesn't have to: Fleet Foxes sound so magnificent it scarcely matters there isn't much to look at. It's not unexpected that the vocal harmonies are fantastic, but what is surprising is how muscular the band sound.
Instrumental opener The Cascades – perhaps the most vaporous track in their oeuvre – turns out to be a red herring. From the moment it fades into Grown Ocean, from recent album Helplessness Blues, Fleet Foxes surge unexpectedly into life. Josh Tillman's drumming is hardly the first thing you notice about their records, but tonight it appear's to be at the core of their sound, a restless, shifting thunder that propels everything along. Even the most delicate songs – Drops in the River, Tiger Mountain Peasant Song – seem transformed into something more forceful, almost anthemic, without sacrificing their subtleties.
It's a hugely impressive trick to pull off. Clearly, something has changed since Fleet Foxes, to use the technical term, died on their arses on Glastonbury's main stage a couple of years back: whatever barrier prevented their music from touching the audience there – nerves? confidence? bad sound? – has been removed. It might help that tonight's audience is so reverential that even Robin Pecknold tuning his guitar provokes a ripple of applause. "You're all so … um … sweet," says Pecknold, sounding more surprised than perhaps he should be at the rapturous response.
Touring until 1 July. Details: www.fleetfoxes.com/tour
