LCD Soundsystem, Brixton Academy, London

James Murphy is the star of the ever-in-vogue LCD Soundsystem. He arrives at the microphone at least three minutes after his band members have already begun the rumbling sound that hints at what's to come. And when he does, the crowd cheer loudly. But it's when the hundreds of tiny emerald spotlights, like leaves lit by moonlight in a forest clearing, start swirling round the stage walls to reveal the six musicians who erupt into the wall of sound that is to last the duration of the set, that the dancefloor opens.

The pulsing funk-groove and scratchy chords of "Us v Them" blast through the huge speakers of Brixton Academy, setting the night's party mood and the cool vibe that LCD Soundsystem encapsulate. Nothing can prepare you for the sheer volume of the music at a live set by this band. While the last album had between one and five musicians recording each track, tonight between them the six play three guitars, two keyboards, synths, two drum kits and countless percussion instruments.

Murphy is co-founder of DFA (Death From Above) Records, whose first vinyl release was The Rapture's "House of Jealous Lovers". Together with The Rapture, LCD Soundsystem brought dance back into New York City, and they hold the trump card for the amalgamation of rock and dance music – the dance-punk-funk genre which Murphy helped foment.

It's what pre-empted the whole nu-rave scene, from Klaxons to the New Young Pony Club. He is also a dab-hand at percussion, playing drums, tambourine and cowbells to precision. But for the king of cool that is LCD Soundsystem, 37-year-old Murphy is not your average frontman.

He awkwardly stabs at the air with his arms and the white T-shirt fails to conceal his contours. He shows his age at times, when he tells the crowd their dancing is "awesome" before asking them to move back and not crush the people at the front. Then later, announcing the last song of the night, he tells the booing crowd: "no really, it is. The Victoria line's still running". He might want an early night, but the fans are fired up.

The first half of the set is almost entirely drawn from the latest album, Sound of Silver, but their radio-friendly and biggest hit to date "Daft Punk is Playing at My House", from their equally well-received self-titled debut album, comes next. The instrumental break when Murphy taps out the impeccable rhythm on cowbells is awesome.

LCD Soundsystem deal in a wry kind of irony best seen in their first release, The Fall-influenced "Losing My Edge" (about being uncool when the "kids" step in), which is sadly missing from their set, and the more recent single "North American Scum", which Murphy tonight emphasises with a sardonic placing of his hands on hips or when he and Nancy Wang clap demonstrably in between vocals.

It's here and in tracks such as "Get Innocuous!" and "Tribulations", when their characteristic throbbing sub bass-lines and pounding drum-beats kick in, that the crowd – largely Murphy's peers who were there at dance music's peak – look ecstatic, and the dancefloor starts to heave.

Similarly, their more pop-dance-rock single "All My Friends" (since covered by Franz Ferdinand) is transformed live, as its emotion of regret is built up to an intoxicating effect beyond the album version.

The encore is the icing on the cake of a spectacular performance. Beginning with their latest single, "Someone Great", the tale of a friend dying, they get even closer to real heart-felt emotion. Their cover of Joy Division's "No Love Lost", which they recently released as a split A-side single with tour partners Arcade Fire, is given heavy bass treatment and suitably frenetic chords. But it's the beautiful finale of "New York I Love You But You're Bringing Me Down", in which Murphy's voice, lamenting the changing personality of his home city, soars over Wang's piano, that leaves the crowd full of nostalgia.

LCD Soundsystem's power is mind-blowing.