About halfway through a Robert Randolph concert, the slide wunderkind kicks his chair back, throws his feet in the air, and starts spinning. This is the cue for the rest of the band to go into double time, and—if it’s 12:01 a.m. on New Year’s day—it’s the cue for three million females to teeter onstage for the dubious privilege of having champagne sprayed at them. For a brief moment, the 9:30 Club feels like Cancun in mid-March: the jam disintegrates, replaced by awkward, arrhythmic dancing.

Then the ladies evacuate and the Randolphs get back to putting on the best live show in the country.

I’ve waxed rhapsodic about these guys before—when Randolph & Fam. played Nissan Pavilion, I was there—but the New Year’s show was less about the peak than about the sustain. (They played for two and a half hours. Which is, literally, five times the duration of their “we’re opening for…Switchfoot?” set in September.) Wednesday’s band was uncharacteristically glutted with guitarists—two in addition to Randolph, one of whom helped on the keys in the unusual absence of Jason Crosby—an unnecessary overcrowding, but then the Randolphs have always been about, you know, inclusion. Danyel Morgan, Robert’s funkier-than-Jesus bassist-cousin, led a typically frenetic workout on “I Need More Love” (celebrating shortly thereafter with a sizable blunt). And if his voice sounded a bit the worse for wear, his stratospheric croon never slips too far below mindblowing.

The group covered Erykah Badu & the Roots (“You Got Me”), riffed on Michael Jackson (“Rock with You”), and closed with a nice medley of “Whole Lotta Love,” “Ain’t Nothin’ Wrong with That,” and “Voodoo Chile.” Is it a constant struggle for Robert Randolph not to turn every song into “Voodoo Chile”? Yes, and the strain’s starting to show. But heavens to Betsy it’s a small price to pay.

Photograph above: The ladays swarm Randolph at midnight. Courtesy of Aaron Wiener.