As the CMJ ’15 Music Marathon continues in NYC, ReNewMusic takes a look back at past events.

They’re well known now on the basis of their two albums – “xx” released in 2009 and “Coexist,” which came out three years later – worldwide tours and independent projects, such as Jamie xx’s “We’re New Here,” his remix of tracks by Gil Scott-Heron, and “In Colour,” his joyous ’15 disc that features as guests his xx mates Romy Madley Croft and Oliver Sim.

But when the xx came from their base in London to New York in 2009 to play CMJ, the trio seemed unprepared, not only for the big time but also for life in public and on stage. The band members I met with – they were a quartet at the time, with Baria Qureshi on guitar and keyboards – at the Tribeca Grand Hotel, were deferential to the point of shyness. Perhaps it had to do with their ages: None had yet celebrated a 21st birthday.

In some ways, their low-key vibe matched the music of their first album, which had been out in the U.S. for about two months. Sparse and inwardly focused, “The xx” straddles the worlds of electronica and shoegaze, with a fondness for R&B in its veins. Percussive notes and simple patterns on guitars by Croft and Qureshi punctuate Jamie xx’s well-considered beats. Dreamy synths and Sim’s bass give the mid-range and bottom a creaminess that worked in tandem with the matter-of-fact vocals by Croft and Sims, who seemed to be addressing each other, and only each other, as they sang.

Eventually, our conversation found its momentum. The band, it turned out, was more assertive when conducting its business: Sim revealed that their label wanted to put out music by the xx in 2007. "We definitely weren't ready,” he told me. “I don't want to put ourselves out there when we're not at our best." CMJ ’09 was a step, not a giant leap, ahead. It was a chance to refine their craft.

The xx played several showcases while in New York, playing in concert music that was a subtle, mysterious enticement. As the video of their set at a party at the hotel reveals, they hadn’t yet quite figured out how to engage an audience – they preferred to stare at their fingers or into the lights – but the performances worked. As it is with the best gigs at the CMJ Music Marathon, a hint of what’s possible shines through.

Aware that the music was both distinctive and alluring, the band’s management and XL Recordings made many smart the decisions in promoting it, perhaps foremost of which was to place tracks in many films and television shows – including TV coverage of sporting events like the Winter Olympics and on BBC’s election programming. “The xx” won the 2010 Mercury Prize for Best Album by an artist or group from the U.K. or Ireland, topping recordings by Corinne Bailey Rae, Laura Marling, Mumford & Sons and Paul Weller, among others. The xx toured aggressively, especially in the U.S.: In 2010, they played the Austin City Limits, Bonnaroo, Coachella, Lollapalooza and Sasquatch festivals – the so-called Big Five.

Thus, in a very short while, the band had found a way to entice a concert audience into their circle. To a visitor who had spoken to them once for less than an hour, it had seemed unlikely that they could do so, not out of disinterest but by what appeared to be a natural sense of reserve. But I withheld judgment – luckily so: Clearly, they had more will and greater vision than they cared to articulate.

Looking back, that it happened for the xx isn’t terribly surprising: They had the music and the right team in place to promote it. But, based on their 2009 visit to New York for the CMJ Music Marathon, that it happened so quickly it is just short of amazing.