There’s a difference between a private party and a veritable secret show. On a Monday night in a converted warehouse space in downtown Pittsfield, Mass., The Low Anthem played the latter.

The sign taped to the front door of the building promising “Secret Show” was a fun wink at the sitch, but the reality is the event could not be promoted—due to restrictions triggered by the band’s gig a few days prior, opening for Emmylou Harris at nearby Northampton’s Calvin Theatre—and the location was not a licensed venue. So there was no password required, no secret knock, but advertisement was strictly by word of mouth and attendance was limited to about 115 people.

The Providence-based band has been featured on NPR, played the main stage of the Newport Folk Festival as well as Late Show With David Letterman, been dubbed “Breaking” by Rolling Stone, and has its third, possibly-breakthrough album set for release in 2011. On the band’s current tour, headliner Harris has taken to joining it for its “To Ohio,” and called it out for her encores as well. The Low Anthem seems to be a judicious soundtrack placement or Nissan ad away from breaking big.

Complimentary Narragansett beer was served in plastic cups, in the sort of gorgeous, raw space (featuring exposed brick and hardwood floors) that would house shows like this all the time in a perfect world (or in the fairy tale version of Brooklyn), but feels like it’ll be turned into a yoga studio any minute. In this special setting, the band delivered a highly focused, at-times-intense 70-minute set featuring a solid helping of songs to be featured on Smart Flesh, the longplayer due out February 22.

The Low Anthem doesn’t present itself as ambassador from another age with the literal-minded verisimilitude of, for instance, The Band—but it has a way of transporting the listener to a place that is neither here nor there, neither now nor then. Rotating among instruments that looked like they might have been played at Lincoln’s funeral, the four musicians captivatingly channeled the sense of sepia-toned-yet-Millennial hope and desperation that is so well voiced on excellent 2008 album, Oh My God, Charlie Darwin.

The show opened with new tune “Matter of Time,” featuring frontman Ben Knox Miller on harmonica and an ancient, foot-pumped organ; Jocie Adams on hammered dulcimer; Jeff Prystowsky on upright bass; and latest addition Mat Davidson playing a metal saw with what might have been a cello bow. The result was a fully enveloping sound, acoustic yet somehow cosmic, the sort of stuff Sun Ra might have been into if his father was Hobart Smith and he grew up in Appalachia. The Low Anthem’s sound is typically more explicitly earthy, but almost always maintains an ethereal whiff of ghosts and prophecy.

Miller’s stage presence was understated to the point of seeming shy; Adams maintained a grim-faced intensity; and Prystowsky seemed like a meditative, bushy-mustachioed sage while on upright bass, but played his spare (though effective) drum parts with an unconcealed glee. Davidson alternated between saw, electric bass, banjo, violin, and one turn on clarinet, displaying a style that sounded self-taught while doing an aww-shucks shoulder bop reminiscent of Ed Sullivan Show-era Paul McCartney.

When Miller sang “I keep a stock of weapons, should society collapse” in the sublime “Ticket Taker“—a class-conscious love song set on the brink of the apocalypse—he voiced a fin du monde anxiety that would be equally at home in the Old Testament or a Tea Party rally. The song opened with a chilling, extended clarinet note from Adams that was so emotive and mournful as to be briefly frightening. “They say the sky’s the limit, but the sky’s about to fall,” as Miller sang, could be scrawled across a bumper sticker on the used Toyota of the generation coming of age amid the Great Recession.

The thing retarding stylistic comparisons to The Band is that The Low Anthem excels at folksy, claustrophobic mood pieces, but has been slow to develop a distinctive sound when hand-cranking up the tempo. The band’s ramshackle take on “Home I’ll Never Be” (right down to the black gaffers tape helping hold together the electric guitar), a Tom Waits adaptation of a Jack Kerouac poem, worked in a bar band sort of way but didn’t transcend its Beatific provenance. So it was encouraging to hear new tune “The Snake and the Lightning Rod,” a barn-burning slab of ragamuffin rock that, we were told, missed inclusion on the upcoming album. “Hey, All You Hippies!” was another successful rocker, this time featuring Adams on the organ and Davidson on electric bass while Miller yelled something about Ronald Reagan and hippies wanting to “fish and live off the grid.” (The hipster reflex of using “hippies” as a straw man to slag off of is more than tiresome, even when not coming from a band prone to moustaches and songs with the word “o’er” in them—but let’s give them the benefit of the doubt until a full lyric sheet emerges.)

This guerilla gig was organized on the sly by the Word X Word Festival, a two-year-old conceptual festival (celebrating the word as written, spoken and sung) created by restaurateur /promoter Jim Benson, a cultural maybe-visionary who has helped spearhead a hipster scene in this post-industrial, gentrifying-but-still-gritty city by sheer force of will and the chutzpah to call a drink made with Pabst Blue Ribbon a “Black and Tan.”

The band’s catalog songs are continuing to deepen through live performance, though it could stand to mix its setlist up a bit more. But the half dozen new tunes brought convincingly to creaky, haunting life at this intimate gig bode well for The Low Anthem’s immediate future. When Miller invited the audience to “play” along with a symphony of cell phone feedback at the end of the humid dirge “This Goddamned House,” the centuries blurred together into something strange but non-specific, beautiful but damaged—which seems a fair way of describing The Low Anthem’s ethos.