Coming on the heels of their heralded self-titled 2009 debut, the xx's new album Coexist offers something few had expected: more of the same. Coexist scarcely alters the UK trio's basic sonic coordinates: plaintive basslines from Oliver Sim, simple, disarmingly melodic guitar lines from Romy Madley Croft, and Jamie Smith's subtle yet effective drum programming and electronic flourishes, all locked in orbit around the emotional core of Madley Croft and Sim's hushed vocals.

It's a simple sound, yet an extraordinarily potent one. Of the many emergent bands who began their careers already thoroughly enmeshed the internet hype cycle's machinery, none have proven as quietly yet thoroughly enduring as the xx.

Swamped with critical praise almost instantly upon The xx's release, the band gracefully transitioned into a stadium-packing indie mega-act, with Smith cannily parlaying the band's fame into a particular sort of indie chachet. After all, the xx arrived in the midst of a sea change for indie music, as a new generation of dance music-influenced sounds came to the forefront. Under the name Jamie xx, Smith built a sterling reputation as a producer and remixer within the emergent overlap between the vanguards of indie and dance music, and many fans and critics expected sounds and ideas from techno, dubstep and house to profoundly steer the xx's direction on Coexist.

Yet as much as the xx feel like a part of the nascent indie/electronica overlap zone, they also feel apart from it. One of the things that made the band's debut remarkable — and a reason why it still resonates so powerfully — is that it sounded utterly original and felt urgently contemporary without bowing to any of indie's dominant trends. And while it's true that dance music has subtly yet unmistakably shaped Smith's approach to sound design on Coexist, the band has largely opted to continue exploring the musical landscape they sketched out in 2009.

It's a wise choice, as the album's lead singles, "Angels" and "Chained," amply demonstrate. "Angels" is a stunning, straightforward paean to love and devotion from Madley Croft, with the bass, guitar and drum machine swelling and receding beneath her wrenchingly lovely vocal performance. "Chained" is even more spellbinding, and stands as one of the band's finest moments to date. Sim and Madley Croft trade fragmented lyrics fraught with tension — "Did I hold you too tight? Did I not let enough light in?," she sings at one point — as lulling cymbal washes and propulsive basslines and drum programming pull the track seductively forward.

The xx's threadbare instrumental set-up allows them to wield silence and rhythm as powerful tools. Nowhere is that more apparent than on "Missing," where the music comes to a full stop only to come rushing back with a fragile guitar line, stark snare hits and bass drum pulses. The multi-segmented "Reunion" finds the band shedding percussion for the first half of the song before diving headlong into throbbing, ethereal electronica.

In the hermetically sealed atmosphere that the xx create, even the smallest experiments create ripples of strangeness. So when Smith's dance music tendencies come to their fullest fruition on the album's penultimate track "Swept Away," they resonate with particular intensity. The song — the album's longest, and perhaps its best — begins with lovely harmonies from Sim and Madley Croft and gracefully spare piano chords. Soon, a supple, hooky bassline kicks in, and the percussion swells, transforming the song a gently throbbing house track. Cymbals, toms and snares abound, creating a microscopically percolating rhythmic texture indebted to early-2000s electronica trends like minimal techno and microhouse. Yet at no point does the music stray far enough from the band's sonic template to feel out of place; the song's experimentation strikes a perfect balance.

Coexist is an enthralling listen, and in the few weeks since I first heard it (we hosted it as a First Listen a while back), I've come to believe it will be as celebrated as the band's debut. It offers a fresh take on an accomplishment that's long been the ideal of a certain strain of indie rock (including but not limited to the xx's most obvious sonic forebears, Welsh post-punkers Young Marble Giants): it performs a kind of inversion of rock'n'roll's ethos, wherein simplicity and delicacy themselves become a kind of potency, a show of strength.