Mogwai, ICA, London <!-- none onestar twostar threestar fourstar fivestar -->

Guitars ring out loud and clear

An air of anticipation hovers over the London live return of the now 11-years-old alt.rock instrumentalists Mogwai. Part of that stems from the Glaswegian five-piece's new manager, Alan McGee, who describes their forthcoming fifth album, Mr Beast, as the finest "art-rock record since My Bloody Valentine's Loveless" - a bold claim, and hard to swallow coming from their manager, but one that's borne out by the resoundingly confident range of the record itself. The clincher, though, had to be Mogwai's admission that they missed playing loud on their relatively gentle last two albums, and that they wanted to revive some of the notoriously ear-shredding noise of their Nineties gigs.

So, which of their namesake furry critters from the film Gremlins are Mogwai tonight: the cuddly furballs, or the ones with teeth? And do their monumental soundscapes sound like cosy relics that were radical only in the Britpop era , or something more vital?

This opening show of the band's five-night residency at London's Institute of Contemporary Arts emphatically asserts that it's the latter. A technical glitch sees the guitarist Stuart Braithwaite quipping about his band's capacity for "deep musical introspection and slapstick", but they actually play with a breathtaking sense of focused intensity.

And with volume. The opening track, "Glasgow Mega-Snake", is a statement of intent in that it's one of two songs on Mr Beast that plays loud-to-loud throughout its savage curves. This is rare for the band, one of whose trademarks was their quiet-to-loud transitions. Confirming their efficacy at sudden shifts, though, Mogwai follow it with the luminescent "Hunted By a Freak", a track from their fourth album, Happy Songs for Happy People, whose hymnal melodies offer a transcendent riposte to the notion that the band have been treading water since their Nineties peak.

In fact, the relative quietness of Mogwai's last two albums and tours sounded like that of a band stripping the sound back to its basic ingredients in order to re-build it with the benefit of experience. The results, on Beast, are often heart-stoppingly potent, mixing brutal guitars with neo-classical piano and deftly deployed electronics that are wholly integrated into well-honed songcraft.

What's striking about Mogwai tonight is that their extremes of delicacy and dissonance are made more powerful by that breadth of musicality. Transitions, like that from the folk-ish finger-picking and the blossoming chorus of their new single, "Friend of the Night" to the lullaby-in-a-hurricane of "Helicon 1", unfurl with a seamless articulacy that few, if any, guitar-bands can match.

Granted, the ominous, piano-led soundscape of "I Know You Are But What Am I" might invite comparisons with the Icelandic space-rock quartet and current press darlings Sigur Ros. But where Sigur Ros essay a kind of prettiness that verges on lofty, vacant preciousness, there's a sense of earthy humanity and a tactile quality to Mogwai's music. The ugly primitivism of the drums on "Auto Rock" is as thrillingly lucid as the gentle empathy of the hushed and ego-less vocals on the plangent "Acid Food".

There's a kind of pure musicality about the results, in that Mogwai use grandiose guitars to create a language of their own, albeit one that's laced with nods to influences such as Slint, the Cure and My Bloody Valentine. Now that they are better than ever at speaking that language, Mogwai's emotional range mines minute subtleties of emotion, rather than simply careening from despair to euphoria.

They close the set with "We're No Here", a heavy-metal meltdown of elemental amp-worrying with a sheet-lightning central passage and a conclusion that tears something transcendent from sheets of feedback. Is that radical? Maybe, maybe not, but it's hard to think of another band who make guitar music sound so simultaneously visceral, genre-stretching and eloquent. No doubt about it, then: Mogwai are magnificent.