UPSTAIRS at the O2 was heaving: sweaty teenagers were throwing shapes next to middle-aged women, the floor was reverberating with the bass from the synth, and then saxophonist Wenzl McGowen got out a two-foot long traffic cone and stuck it in the end of his instrument to make a kick-ass Alpine horn.

The crowd. Went. Nuts.

The three Brooklyn 20-somethings who call themselves Moon Hooch – James Muschler, Mike Wilbur and the aforementioned Mr McGowen with his traffic cone – rocketed to international fame after videos of them whipping up frenzies on the New York subway went viral.

If you're not familiar, the set-up is simple: one drummer, two saxophones – but this aint jazz: furiously fast drum 'n' bass beats battle with cheeky, melodic and frequently aggressive parping, wailing and foghorn fury bass lines.

The impromptu raves they invariably caused on the New York underground eventually forced the NYPD to ban them from performing at certain locations, so they took their show on the road – including a stop-off in the city of dreaming spires.

Safe to say when Adolphe Sax invented his eponymous horn in 1840, this isn't what he had in mind.

As soon as the boys get on stage it's hands in the air and howls of approval.

They kick off with a typically cheeky nursery rhyme little melody – the two saxes duelling back and forth in a hypnotic harmony.

Then the drums kick in and it turns into a dubstep dungeon, saxes wailing with mad, raw energy.

Not long into the set Mr McGowen ditches his horn for a synth that pumps out obese bass lines.

After a while, there was so much synthesizer you could almost dispense with the saxes, but Mike Wilbur broke up the rave halfway through the set by demonstrating a hidden talent for spoken word poetry, before we dived back into the musical melee.

The refrain of his poem was "this is a state of emergency", and with the two golden horns wailing like wounded animals, police care sirens or foghorns warning of ships on a shaking sea, I couldn't think of a better description myself.