Calvin Harris, Scala, London<br>Devo, Forum, London

Calvin Harris has come up with a few new riffs, and his audience has already started singing them

Who's the lead singer of Calvin Harris? Once upon a time, the answer to that question wasn't as self-evident as it sounds. When I first saw him, in a pub on the 2007 Camden Crawl, he was very much the midfield playmaker in his own band. Nowadays he's centre-forward.

Tonight, Calvin Harris stands before us naked – or as naked as a gold velour trackie over a black T-shirt and jeans will allow – his only crutch a small console-like gadget of dubious musical relevance. (Conceivably, he's posting on Twitter.)

Comeback single "I'm Not Alone" began with Harris singing all but unaccompanied and, like much of his forthcoming second album, admitted to feelings of vulnerability and doubt. It takes guts to show vulnerability, and Calvin's found 'em.

A sleepy-eyed Scot who often comes off as laconic to the point of coma, he's unexpectedly animated tonight, roaring, "London, are you ready to go off?", like we're a week-old pint of semi-skimmed. And, for much of the show, this corner of London does go off, like a bottle rocket.

Everyone's hatin' on Calvin Harris nowadays: serious techno-heads, cooler-than-thou indie scenesters, even Calvin Harris himself. But after a No 1 with Dizzee Rascal last summer, and a No 1 in his own right now, he must be doing something right.

"Acceptable in the 80s" is remixed tonight; Harris confesses on mic that he's sick of that song. Well, tough. Without it you'd still be stacking shelves. C'mon man, give us the sugar, not just the salt.

Whatever you think of the I Created Disco material now, you forget how irresistible it was until "Disco Heat" booms at you from a massive PA. The backdrop and the merch may still show the visuals from that record, but on the new material, it's all change. Calvin's been speaking of "stadium dance", and there's a lot of that: his erstwhile choppy staccato style's made way for monumental three-note riffs. (And, it must be said, doom-laden Numanesque instrumentals which leave everyone bemused. Oh, and what sounds uncannily like a cover of DJ Jean's "The Launch".)

Forthcoming single "Ready for the Weekend", with its "I'm putting my shoes on ..." chorus aimed squarely at that all-important footwear demographic, is a hands-in-the-air anthem in waiting, and the closing "I'm Not Alone" has the chip shops around King's Cross echoing afterwards with people singing the riff. Let the Harris haters keep on hatin'. The chip-eaters and the shoe-wearers know the score.

Mention the word Devo and the epithet "post-punk" will never be far behind, but in truth the Akron art rockers' origins were pre-punk, having formed in the aftermath of the massacre of anti-war protesters at America's Kent State University in 1970.

As founder Jerry Casale has explained to Simon Reynolds, "After Kent, it seemed like you could either join a guerrilla group like the Weather Underground, actually try assassinating some of these evil people ... or you could just make some kind of whacked-out creative Dada art response. Which is what Devo did."

A product of their time, and also of their place: one of the first bands to self-identify as "industrial", their jerky rhythms mimetic of the Ohio rubber capital's factories. The specific desire was to make "outer space caveman music" (Casale), the theory being that "the more technology you have, the more primitive you can be" (Mark Mothersbaugh).

For a long time, Devo disappeared from the discourse entirely. Suddenly, though, every "angular" post-punk revivalist act was ripping off Devo's chops, and their 1979 debut album Are We Not Men? (We Are Devo), performed in its entirety tonight, sounds easily contemporary enough to be a current release. Admittedly, Virgin would never sanction a song like "Mongoloid" today. For that track, Mothersbaugh – looking like a mad professor played by a middle-aged Rick Moranis – incongruously jiggles pom-poms.

For old men, and for art pranksters, Devo rock harder and louder than you'd ever expect. The name carries a double meaning: slang for "deviant", and short for "de-evolution", which crops up in the one bit of banter. Casale asks whether the intervening 30 years have shown that de-evolution is occurring. The response is universal assent.