Midway through the enthralling new Avett Brothers CD, Live, Volume 2, Seth Avett makes clear in an aside that what we are experiencing is a different kind of musical entity than the sometimes overly precious commodities we have come to expect in our digitally enhanced age. Introducing “Wanted Man,” one of only two covers in the collection, he tells the rapturous crowd about a run-in with fellow North Carolinian Doc Watson, one of the band’s unavoidable influences. Backstage at a concert where they were opening for the legend, Seth asked Watson’s permission to play “Wanted Man,” first heard by the band on a Watson album. A snickering Avett relays Watson’s response: “It’s not my song. I don’t give a damn if you play it or not.” More than a simple misunderstanding about the song’s provenance, the exchange underscores a rift between how two generations hear recorded music. To the young Avett, who grew up steeped in studio-manufactured music and witnessed the Napster wars, recorded sound implies propriety. In Watson’s world of traditional music, where a song is more obviously an ongoing event that mutates a little more with every performance, authorship is a dubious idea—and often beside the point.

In the age of mechanical reproduction, all music can be Muzak. Given the right cubicle or dental chair, the Sex Pistols’ “God Save the Queen” can be just as narcotizing as an instrumental version of Henry Mancini’s “Evergreen.” What renders a musician’s labors merely pleasant white noise—a distraction, say, from the unbearable act of vacuuming—is not the quality of the performance but the fact that, as a recording, it can be controlled by the listener. Before the existence of recording devices, if you were lucky you could have expected to hear a certain masterpiece once in your lifetime. Now, you can put any old favorite on infinite repeat, until the emotional arc of your first encounter is squashed flat by a million identical listens.

When Alan Lomax traipsed around with a tape recorder, capturing as-yet-unknown American folk heroes for posterity, his device was exactly what its name denoted: a machine that made records of audible moments. People didn’t expect these records to be as good as the original. But technological advancements and their innovative application by the likes of Phil Spector, Brian Wilson, and George Martin inverted our expectations. These studio wizards recorded larger-than-life arrangements that made musicians in the flesh sound flimsy and imprecise to the average ear. The result, in some respect, was the domestication of rock and roll’s wild bacchanal, its only living, unpredictable element the fingers of the listener on the on/off button.

It would be a sore injustice to suggest that the Avett Brothers are nostalgic throwbacks. Their music is, in fact, both comfortably familiar and entirely fresh. The circuit of traditional music festivals is riddled with museum pieces meant to do little more than conjure a bygone age, to give blood to Smithsonian relics. When Seth Avett (acoustic guitar, vocals, stomp cymbal), Scott Avett (banjo, vocals, stomp drum), and Bob Crawford (standup bass, backup vocals) show up in this context, as they did this year at Doc Watson’s Merlefest in North Carolina, they tend to blow the house down with their uncanny mix of disarming earnestness, welcome irreverence, and crash-bang musicianship. While their most recent studio-recorded CDs (Carolina Jubilee and last year’s Mignonette) represent two of the most underappreciated pop-music offerings of recent years, the band is first and foremost a group that must be experienced live, and their new CD captures them in all their perfect, melodic messiness.

On these tracks we hear all the elements that make the Avett Brothers so much bigger than their contradictory parts and minimalist orchestrations. They are a post-punk power trio of the acoustic sort, owing as much to the austere wailings of the Louvin Brothers as to Kurt Cobain’s shrieks. The breathtaking emotional range of their songs makes wide way for driving pop tunes, baleful and deeply satisfying ballads, and foot-stomping old-timey romps. Their always-lucid lyrics can be wry and disarmingly heartfelt, often simultaneously, and if sometimes a shopworn image drops in it only amplifies the air of the boys’ innocence. The tender melodies of their nearly flawless ballads, such as “November Blue” and “My Last Song to Jenny,” are immediate enough to hush a crowd and complex enough to endure a hundred listens. Their stage personas encompass the trashing of banjos and the good down-home sense to ask their musical elders for permission to play a song. Unlike some revisitors to the old-timey strains who can’t resist smirking or underscoring the southern gothic, the Avetts address the traditional secular themes—love (new and lost), chronic traveling, passion crimes—with unblinking originality, humor, and a lack of presumptuousness. “A Lot of Movin’,” for instance, distills the “ramblin’ man” trope of American music to perpetual motion for its own sake. “November Blue,” on the other hand, treating the related theme of diminishing love, laces the hopeless speculations surrounding an imminent departure to a melodic line that unravels somberly out of the aching half-step of the first two measures, and the accumulated, circular effect is beautifully reminiscent of Townes Van Zandt’s similarly themed “Come Tomorrow.”

And just when you decide their string ties, bushy beards, center-parted hair, and shirts buttoned to their adams apples are purely the stuff of theater—nothing more than something for them to undercut with their impious screams—they muster a song like “Offering,” a quiet and unqualified testament to settling down, in which the two brothers draw out a harmonized note, Simon and Garfunkel–style, on the line, “I dream of children we can call our own.” When, shortly after the line’s resolve, the banjo and bass kick in to the delight of the audience, the effect is as powerful as any studio—orchestrated wall of sound, as it becomes clear how adept these musicians are at allowing their songs to be shaped by an audience’s reactions.

It is telling, maybe, that the most ambitious and conceptual song on the CD, “Complainte D’vn Matelot Mourant,” can’t quite lift itself up above the clink and chatter of the crowd. The song, while stretching the outer limits of the band’s range, works well enough as a studio recording. But bar crowds don’t take kindly to displays of introspection; they can access those themselves anywhere by thumbing their iPods. What they want, judging from their roars, are songs such as “Love Like the Movies,” a wry pop critique of pop culture (in this case, Hollywood). The song admonishes all those who prefer the fanciful recordings to the messy actual (“Real life is more than just two hours long”), and its unrelenting bass line and finely tuned harmonies, which are significantly more raucous than the docile studio version on Carolina Jubilee, seem as much a result of the audience’s energy as the musician’s intention. Together they create a record of what a good live performance is, an energetic intermingling of musicians and listeners where no one has control, in which where the songs come from or who authored them are beside the point.