One of synth player Christopher DeNitto’s remarks from the Dead Fame interview I posted on Tuesday was bouncing around my brain later that night during The xx’s concert at The National. When talking about his group’s writing process, DeNitto evoked the saying that “A song is never finished.” Tuesday’s show demonstrated that The xx are a group that understands how true that adage really is.

In fairness, I should confess that before I set foot in The National, I knew something was up. This short Rolling Stone article tipped me off to the fact that the English trio had devised new arrangements for some of their older songs, in an effort to keep things fresh for fans who have been playing the band’s self-titled debut effort ad nauseam since its 2009 release.

In some ways, this isn’t surprising. The xx looms uncommonly large in the world of remixes, re-works and edits. As I wrote around the time that their sophomore album, Coexist, came out, “I have a hard time thinking of a group whose new music can clutter Soundcloud with remixes as quickly as The xx’s can.” And it’s not as though they’re passive participants; Jamie Smith joins in, periodically releasing re-worked versions of xx songs online, including the one at the bottom of this post.

HOWEVER, as expected as this type of tinkering may be, live performances are a different story. Put yourself in the band’s shoes. You’re on tour, playing to thousands of people each night. In this case, you’re playing in the state of Virginia for the very first time, going so far as to apologize to the crowd for not having visited sooner. Then you take a song those people have been drooling over for almost 3 and a half years… and you mess with it. You revise it. No matter how thoughtful your revisions may be, that’s ballsy.

My favorite example came during “Crystalised,” which was released on their first record. Its most memorable detail — the “Ayee-ayee-aye” vocalization that pops up at several of the songs transition points — was largely withheld, and you could hear the crowd singing that part in the place they expected to hear it. Were people pissed? Did a mass walkout ensue? Nope. People cheered loudly at the end of that song, just as they did the others, and I heard nothing but positive remarks when leaving the venue. (Well.. positive remarks and people excitedly talking about what merch they were going to buy. I’m (somewhat) happy to report that I was on my best behavior,  barely resisting the black zip-up hooded sweatshirt with a giant, white “X” on the back.)

What’s really interesting is how this notion of withholding echoed throughout the evening. Jamie’s beats calmly and expertly toyed with our expectations, so much so that I heard a woman behind me trying to guess when the bassiest elements of one song were going to drop. The lighting worked in similar ways, holding back the brightest elements for utterances of the word “Up” in set closer “Infinity,” which itself is about bottling up carnal urges. And front-liners Romy Madley Croft and Oliver Sim got in on the act as well, straining their voices sparingly and engaging in a smoldering tug-of-war with one another’s personal space, closely mimicking the unconsummated power struggle between two ballroom dancers. At one point, Sim actually wrapped himself in his mic cord and slowly lifted it back over his head, a move that deserves some sort of award for obliterating the line between filthy and family-friendly.

Even still, with all that was pent up, and as thick as the air was with the absence of things, it was an extraordinarily satisfying show, better than I could have hoped it would be. The xx have distilled their formula in way that reflects real maturity and self-awareness, and I can’t imagine how potent that brew will be the next time I have the opportunity to see them live. I hope that opportunity arises sooner rather than later, but I suppose a little built-up anticipation can’t hurt.

Listen to Jamie Smith’s re-work of “Sunset” below and click here to snag the original version on iTunes.

The xx — “Sunset” (Jamie xx edit) [Soundcloud]