They're officially better than Depeche Mode and the Yeah Yeah Yeahs, having beaten both to win a best album Grammy earlier this year. They were the most blogged about band in 2009 according to internet buzz generators The Hype Machine, and their last album has gone gold in the States.

Gallic chic: left to right, Phoenix singer Thomas Mars, bassist Deck D’Arcy and guitarists Branco and Christian Mazzalai

Lead singer Thomas Mars is boyfriend to indie film queen Sofia Coppola and fashion designer Hedi Slimane has worked as their art director. So, are Phoenix the coolest band you've never heard of?

At the end of the month, the four childhood friends (including a pair of brothers) originally from the affluent French suburb of Versailles, return to London for two sold-out nights at the Roundhouse — their biggest concerts in Britain to date, hopefully cementing their crossover from cult indie concern to bona fide rock stardom.
 
“We grew up obsessed by English music —My Bloody Valentine, The Jesus and Mary Chain — but we are not very good rock stars,” says Mars, with a perfectly timed Parisian shrug. The elfin lead singer of the band “with no leaders” makes for an idiosyncratic frontman — charming, erudite, but quiet and slim on ego. “I think I am probably the worst rock star. It's just a practical fact,” adds Branco, the lead guitarist looking every inch the Gallic rock proposition: all thick specs, a shag of thicker hair and an immaculately chic wardrobe. “I don't go to the parties,” he explains, “we find them too boring.”

Star couple: director Sofia Coppola with Phoenix singer Thomas Mars — they are now expecting their second child

It's a curious statement, not least because over 10 years and four albums, Phoenix have been soundtracking exactly the kind of party where you'd expect to find all the beautiful people. The quartet, which also includes Christian Mazzalai on guitar and Deck D'Arcy on bass, trade in ethereal guitar pop, riffing with and without irony from Seventies California, Miami Vice tinted soft-rock and French electro. It shouldn't work. Judging by the consensus-shifting bands now indebted to Phoenix's sound though — MGMT, Empire of the Sun, Passion Pit and so on — the clever pop of singles like Listzomania, Napoleon Says and Everything Is Everything is finally catching on.

“Sometimes I hear bands and I know they have been listening to Phoenix. I'd feel bad mentioning names but I see similarities or things influenced by us,” admits Mars. He's referring to woozy, summer-drenched pop; it's not landfill indie guitar music and it's not pumping chart electro.
Think the Strokes with synths, going disco but with dafter, more mysterious lyrics. “We don't try to make sense,” says Mars, who sings the catchy tunes in impeccable English with a West Coast accent. “In lyrics, we end up deleting everything that makes too much sense. [Our songs] are the opposite of a message, they are cryptic.”

Their latest album, Wolfgang Amadeus Phoenix, released last May, has gone on to outsell their other three albums (United, Alphabetical and It's Never Been Like That) put together, winning them that Grammy for Best Alternative Music Album. Fan-made videos for Phoenix songs have gone viral on the internet and the band have performed everywhere from the Hollywood Bowl to primetime US television on Saturday Night Live. “It's been building slowly and for sure, it's better this way,” says Branco. “The idea to fulfil all your dreams early on … what do you do then?” Later this year, they'll be recording their own MTV Unplugged session as the channel revives the series, and making a short film with Sofia Coppola.

“Sofia and I have never worked together really,” Mars says. “We make music, she picks songs she likes for her films,” he says softly. Close watchers of Coppola's Oscar-winning Lost In Translation will remember Phoenix's Too Young, Bill Murray and Scarlett Johansson's synth-heavy swan song to hedonism. At the time, the director was married to filmmaker Spike Jonze, but the couple filed for divorce two months after the film's release in 2003. Mars and Coppola are now expecting their second child together in the summer.

The couple have also recently spent a few months in LA, while Coppola worked on a short film inspired by a Phoenix track, Love Like a Sunset. As they are usually based in New York, I ask if the couple would ever consider moving permanently closer to Hollywood. “No! I would never live there. LA is a very weird, desperate place. It doesn't reveal the best in people.” How so? “It destroys them. Look at [Kurt] Cobain, Prince — they all got screwed by LA.”

The band's ramshackle approach to the music industry — “we make a great effort to remain semi-pro” reveals Branco — might explain why they only now seem on the verge of making an impact on British audiences. “We've been something like 50 times.” Branco adds, “but we feel a resistance too, we haven't conquered London yet.” I can only imagine that that is about to change.
Phoenix play the Roundhouse, NW1 (0844 482 8008; www.roundhouse.org) 29-30 March