Three years after its breakout debut, the xx returns with a plan to keep building buzz from the underground up

The Internet shared a collective swoon on July 16, when British trio the xx unveiled "Angels," the first single from its highly anticipated sophomore album, "Coexist" (Young Turks/XL), out Sept. 11.

The hushed love ballad -- sung in half-whisper by vocalist/guitarist Romy Madley-Croft, against a distant space guitar -- was accompanied by a video, if one could call it that. The single shot was trained on a light-refracting liquid of some kind -- trembling and morphing ever so slowly, and not necessarily in reaction to the music. The rainbow implied sky; the desert-colored backdrop, earth; the moving globules, water. Somehow, the xx had found sensuality in minimalism. The clip has logged more than 3 million YouTube views.

"The band had a strong idea of what they wanted," xx manager/Young Turks founder Caius Pawson says. "Luckily [graphic artist] Davy Evans at the label had already done a similar project, so the two came together very naturally. They've done a video like that for every song on the album."

The xx -- Madley-Croft, bassist/vocalist Oliver Sim and DJ/producer Jamie Smith (original member Baria Qureshi left in 2009) -- released debut album "xx" in 2009, to nearly universal acclaim. It won the United Kingdom's coveted Mercury Prize; sold more than 380,000 U.S. copies, according to the label; and landed on year-end top 10 lists worldwide. Most recently, the album placed at No. 15 on Pitchfork's People's List poll, which asked the tastemaking site's audience to select its favorite albums of the last 15 years.

"It's overwhelming and extremely flattering," Sim says of the Pitchfork placement. "So many albums in that list mean so much to us that it's incredibly surreal to see."

Even the sales picture implies that xx has transcended its notable debut and is on its way to becoming a classic. "The first album's sales to date look surprising to many people, because it's quietly and steadily sold over a three-year period," XL head of U.S. operations Kris Chen says. "There's still a lot of life in it, and it will eventually reach 500,000 and 1 million sales points as people continue to discover it."

Smith's production turns also helped the band bob above the underground: His remix of Gil Scott-Heron's "I'll Take Care of You," with Madley-Croft supplying some additional guitar, was used within Drake's mega-hit "Take Care," making the young producer an in-demand studio star. (He's reportedly collaborating with various pop stars currently.)

But if the band felt pressure going into Coexist, the end result doesn't show it. The album is bolder without losing any of the xx's particular brand of delicate beauty: the use of silence and restraint, of ache rather than yell. Even when experimenting with kick drums, as on "Swept Away," nothing feels forced. It's no surprise to learn that the members were listening to a lot of Sade during recording, according to Sim.

"I suppose it's cliche to say our second album is more mature than our first, but it's inevitable since we were teenagers when we made xx," Sim says. "Our perspective on the world is different. Our approach to making the record was broadly the same -- we just had a bit more experience this time, and confidence."

Chen says brand partnerships and social media onslaughts aren't part of the marketing plan for the record, which will follow the "Angels" video, in tone as well as content. "Perhaps doing things in a simple and straightforward fashion and letting the music speak is unique," he says. Second single "Chained" is going to radio now.

In October, the xx will begin a 19-show North American tour that will take it from Vancouver to Baltimore, and from traditional venues like Boston's House of Blues (Oct. 25) to uniquely theatrical ones. The band will play two nights at New York's Paradise Theater, an old movie house in the Bronx (Oct. 26, 28); a waterside set at the Cosmopolitan Las Vegas' chic Pool (Oct. 10); and a small show at Hollywood Forever Cemetery in Los Angeles (Oct. 13) after a night at the 4,000-capacity Hollywood Palladium.

"The U.S. is full to the brim with amazing venues," says Pawson, who notes that he and the band's agent, Tom Windish of the Windish Agency, "went through thousands of them. We might have driven him slightly mad."

For Sim, who says the band is looking forward to playing "the more dance-y tracks on the album," the live show is a critical piece of the xx. "Going to see bands we love play is a very treasured experience for us, so we feel that if there's anything we can do to make our concerts special, that we owe this to our audience," he says. "We're lucky enough to be invited to play all over the world. It wouldn't be fair to be complacent and not put the effort in."

"Awards and prizes aren't the defining aspects of this band. Their success is measured in the love they get from fans," Chen says. "I watched a girl openly weeping at a show recently in the second they took the stage. That's recognition."