MGMT, Academy, Birmingham<br/>Mercury Rev, Concorde 2, Brighton

At a time when New York is getting too cool for its boots, to the extent that the New Musical Express is running fawning articles on exactly which private university is the hippest place for forming a band, there's a strong temptation to bring it down a peg or two. MGMT, alumni of the fee-paying Wesleyan Uni and probably the biggest name of the NYC crop, would appear an obvious place to start the backlash. But they're not.

There is no cutting-edge movement that can contain MGMT. Andrew VanWyngarden and Ben Goldwasser, with their mystical melange of soulful psych-pop – imagine Hawkwind meets the Chi-Lites – have created music that exists outside the timeline. Far from the war-painted weirdos of their record sleeve, the on-stage incarnation consists of five regular indie blokes in black T-shirts. Disappointing, but perhaps they're fans of Flaubert. ("Be regular and ordinary in your life, like a bourgeois, so that you may be violent and original in your work.")

"Violently original" isn't strictly accurate. MGMT's wide-eyed, hymnal rock has precursors in the likes of Grandaddy, Super Furry Animals, Polyphonic Spree, Mercury Rev (with whom they share a producer in Dave Fridmann), and Flaming Lips (also Fridmann-produced), whose Wayne Coyne could teach MGMT a thing or three about putting on a show. MGMT, notorious for their technical hitches, are sometimes so sloppy it verges on insulting, turning their backs on the audience and twiddling machine heads for minutes on end. Surely they have roadies and techies for that sort of thing?

It's especially frustrating, because when MGMT are on song, they can lift you out of yourself. In between, it might as well be downtime in a rehearsal room. VanWyngarden tries to make a knowing joke of it: "How do you like this tuning up between songs vibe? I'm just doing it to take the edge off." Telling a band as blissed-out as MGMT to "tighten up" almost feels blasphemous. But c'mon, MGMT. Tighten up.

It's worth the wait, though, for "Time to Pretend". Stupendously candid about the cocaine-hoovering, model-shagging life of a band on the rise, it's clear-sighted, even visionary about their likely future: "The models will have children, we'll get a divorce/we'll find some more models, everything must run its course..." Even better, for me, is "Electric Feel", in which the ghost of Curtis Mayfield waltzes with Kate Bush's "Running Up That Hill" (whose rhythm it unashamedly borrows). Channelling the existential thoughtfulness of, say, the Brothers Johnson version of "Strawberry Letter 23", it's a masterpiece of passive soul, imploring its object "Ooh girl, shock me like an electric eel...". I listen to it at least three times daily, in disbelief and awe.

There can be few bands who have reinvented themselves as comprehensively as MGMT's forebears, Mercury Rev. Following the departure of singer David Baker, they underwent a revolution, abandoning frazzled, wayward wig-outs such as "Chasing a Bee" for a symphonic classicism which peaked with the classic Deserter's Songs album. This year's Snowflake Midnight sees another rethink, although this time, to paraphrase Partridge, they haven't revolved, they've evolved.

It's a partial move back in the direction of sonic obliteration. Songs such as the beautiful "Snowflake in a Hot World" combine melody with a skittering electronic undercarriage, as though MR are belatedly acknowledging the existence of dance music, and older songs, such as their parallel-universe Bond theme "Dark Is Rising", are tonight augmented by digital detonations and black noise.

Whatever may be unfolding around him, leader Jonathan Donohue is an endlessly watchable frontman, the circus ringmaster and the coquette, his face a squabble between eyeliner and five-day stubble. Thankfully, he's smart enough not to scuff up Mercury Rev's finest jewels. "Holes" is one of those songs which, even though the lyrics may be borderline nonsense, is somehow supremely moving when sung in Donahue's straining voice.

Whichever direction the Mercury Rev spaceship may be heading right now barely matters. The point is that it transports you.