SAN FRANCISCO--While the Waybacks' CD release party last night in San Francisco was a festive occasion unto itself, the cause for most of the commotion arrived four songs into the evening. After the band had unwrapped a few of their new tunes and officially welcomed new fiddler Warren Hood, the next addition to the stage needed no introduction.

The capacity crowd roared as soon as it caught sight of Bob Weir. Clad in ghostly white, the former Grateful Dead guitarist strode to center stage clutching an acoustic guitar by its neck. He acknowledged the adulation with a nod, strapped on his guitar, and quickly led the Waybacks into the Dead classic "Jack Straw." Immediately, the oak floor of the Great American Music Hall began to buckle from dancing that would continue throughout both sets.

From there, the Weirbacks, as some have called this collaboration, steamed straight into "Big Iron," a Weir staple since even before his 1976 Kingfish recording. By the end of this tale of the Old West, Weir, sporting an outlaw-caliber mustache, seemed like a gunslinger, hunched over and hammering out power chords through his electronically enhanced acoustic cutaway.

Waybacks lead guitarist James Nash explained the special occasion during a break between songs: "Tonight we're playing stuff we wanted to play, instead of what we already knew." This served as a potent dose of foreshadowing for what was yet to come.

Crowd-pleasing Grateful Dead numbers such as "Casey Jones" and "Brown-Eyed Women" mingled with Johnny Cash's "Big River" and The Band's ever-popular "The Weight." Weir took over lead vocals much of the night, occasionally growling and screaming, especially when tackling the Rolling Stones songs "19th Nervous Breakdown" and "The Last Time."

But even those raucous renditions didn't prepare the crowd for the powerhouse punch of Led Zeppelin's "Kashmir."

The ornate, frescoed theater shook while Weir wailed a la Robert Plant over earthquake-quality rhythms anchored by Joe Kyle, Jr. bowing his stand-up bass. Who'd have thought that one fiddle and one mandolin could do such justice to the strings section of that classic rock anthem?

The night's highlights also veered outside of rock and roll. Some of Weir's most expressive and impressive guitar work came to light in a New Orleans-style number in the Waybacks' repertoire. Perfectly complementing Warren Hood's sweet, smooth vocals, Weir brandished a slide and coaxed a soulful solo that elicited appreciative shouts from the floor and balconies.

San Francisco isn't the only city lucky enough to catch a glimpse of this potent conglomeration. This weekend, the Waybacks will serve as Weir's backing band for two performances at North Carolina's popular MerleFest.