Life on the road for a young independent band can get pretty weird pretty quickly. But as the late Hunter S. Thompson put it best, “When the going gets weird, the weird turn pro.”

Witness Friday evening’s gig in Duke’s Bohemian Grove Bar in Allentown, where Pennsylvania “jamgrass” six-piece Cabinet were faced with a family emergency immediately upon arriving at the venue. Fiddle player Todd Kopec took a call from his family, and the news was such that he had to be driven immediately to Buffalo Niagara International Airport for a hasty flight back home.

Clearly shaken by whatever their friend and bandmate was going through, the other five members of Cabinet decided to soldier on and play the show. We who were in attendance were lucky the band made that decision. Cabinet, as it turns out, is a tour de force, a bluegrass/old school country/folk wrecking crew unafraid of the lengthy improvisation more common to jam bands and jazz ensembles than to American roots music.

Certainly, the young band has been greatly influenced by the music of Bill Monroe, the father of bluegrass. The formality of the tradition – its blend of instrumental virtuosity and keening vocal harmonies – hung over everything Cabinet did on Friday. But just as evident was the band members’ love of the jam, which lent a Grateful Dead-like ambience to the proceedings. Since the Dead’s Jerry Garcia was a folk and bluegrass banjo player prior to taking up the electric guitar, there is a continuity there ripe for the exploiting, and Cabinet did this with panache.

Principally promoting its recently released fourth studio album, “Leap,” the band – JP Biondo on mandolin and vocals, his cousin Pappy Biondo on banjo and vocals, Dylan Skarsky on double bass, Jami Novak on drums and Mickey Coviello on flat-picked acoustic guitar – also offered bits of its previous albums, and made it plain that the buzz spreading across the Northeast regarding its in-concert prowess is entirely justified.

The five musicians put their worry over Kopec’s situation to the side, and took to the stage with authority. Immediately, the interplay between the Biondos was apparent, as Pappy’s jaw-dropping banjo technique found him spitting out rolling arpeggios that wrapped themselves around JP’s rapid-fire melodic lines. Echoes of Bela Fleck & the Flecktones were impossible to miss. This was bluegrass played with the technical brilliance of jazz.

An early “Poor Man’s Blues” revealed another trick in the Cabinet – beautiful three-part vocal harmonies, handled by the Biondos and guitarist Coviello. These elevated “Doors,” the opening track on “Leap,” toward the sublime. Coviello soloed here as well, trading licks with the two Biondos, his dazzling flat-picked lines suggesting he’d studied masters of the form like Doc Watson and Jerry Douglas.

An interpretation of Bob Dylan’s “Diamond Joe” got the crowd, gathered tightly in front of the stage, into a hootenanny-like frame of mind, and that elevated celebratory air remained, as the Cabinet men tore through “Carry Me in a Bucket,” “Coalminers,” the delirious instrumental “Flop-Eared Mule,” and the banjo-led throwdown “Shifty Shaft” without the ferocity of a troop of thrash-metal merchants.

In addition to blowing the minds of the assembled, the Cabinet show underscored a sad fact about the more mainstream strains of roots music. Yes, we’re talking about pop acts like Mumford & Sons and the Lumineers, immensely popular bands that dress a lot like the guys in Cabinet, and play similar instruments, but can boast very little of the skill and virtuosity that underpins true bluegrass and rootsy folk. Cabinet could easily continue to grow, and even flourish, within the jam-band scene that has already embraced them. But the mainstream success of a pseudo-bluegrass band like Mumford is likely to elude the group. Fine – that makes it easier for us to enjoy such a fantastic band in an appropriately intimate venue like Duke’s.