SELLING OUT YOSHI'S on a Monday night ain't no easy thing, particularly when the weather's chilly and practically no one has heard of your band.

It helps, of course, to have family and friends. Dave Ellis and Zoë Ellis had a whole bunch of both turn out to hear them co-lead an ensemble they call Zadell. And there were lots of fans who may not know the siblings personally but have been following their music during the past decade. Tenor saxophonist Dave has garnered a big-time rep through his straight-ahead jazz gigs and recordings, as well as his work with the original Charlie Hunter Trio and Grateful Dead alumni groups Ratdog and the Other Ones. Zoë's résumé as a vocalist includes stints with the Oakland Interfaith Gospel Choir, the Mo'Fessionals, Cleveland Lounge, the Braids, and currently both Slammin' and the Glide Ensemble.

"I'm just the nice Jewish girl at the Methodist church," she quipped during the performance. "That's what you get when you're raised in Berkeley."

She was tipping her hat to members of the choir at Glide Memorial Methodist Church who had come to see her and her brother's band, as well as to a multicultural upbringing. Their African American dad and Jewish English mom, both retired from UC Berkeley, were also in attendance.

Zadell, who were making their first appearance in four years, combine the Ellis kids' names as well as their associated musical cultures. They mix Dave's jazz perspective with Zoë's grounding in R&B. Such fusion is nothing new; one hears it every day on KKSF-FM and KBLX-FM. "Smooth jazz," as radio calls it, often features jazz instrumentalists and soul singers performing together, though it's too often watered down to pabulum. In Dave and Zoë's hands, however, the blend proves plenty powerful.

Dave, his clean-shaven head, shirt, and slacks all radiating an orange glow under Yoshi's yellow and red stage lights, kicked off the set with the band's four-man rhythm section on an original tune titled "King of Things." With bassist Nate Pitts and drummer Tommie Bradford locking into a fat funk groove, the saxophonist negotiated the song's serpentine head in molten tones. He paused at times for guitarist Cedricke Dennis to answer his cries with volume-warp moans, then ripped into a series of improvised choruses filled with impassioned Coltrane-esque overtones.

The opening selection briefly segued into Weather Report's "Teen Town" before Dave brought his sister and harmony vocalists Bryan Dyer and Kisha Griffin to the stage for "Could You Ever," a rumba-flavored soul song from Zoë's Cleveland Lounge days. Nicely color-coordinated with her older brother in a dress of orange, auburn, and black, and her hair a yellow and brown frizz, Zoë sang in a resonant contralto reminiscent of English R&B singer Des'ree. "Could you ever be a mountain watching over me?" she asked urgently, adding different gospel melismas with each repetition of the hook, though her intonation occasionally faltered. The rhythm section then dropped suddenly, as Dave tore into a tenor solo and Zoë clapped a clave before pianist Mike Aaberg began pumping a salsa pattern. Zoë eventually added some scat to the syncopated fury.

The set also included two originals by Zoë, two by Stevie Wonder – "Contusion" (a largely instrumental number with tricky time-signature shifts) and "Shoo Be Doo" – and "I Can't Make You Love Me," a Bonnie Raitt ballad with lots of sustains that allowed Zoë to showcase her warmth of tone. Dave switched to soprano sax at times and, on a couple of tunes, to EWI, a wind-blown synthesizer from which he produced a deep, annoying buzz. (A baritone sax would have worked better.) Zadell's brightest moments came on the vamps of many tunes. As Dave blew with abandon, Zoë joined in wordlessly, leaping registers with ease and landing on pitch each time – achieving a rarefied form of musical interaction in which common blood is surely a major factor. Zoë Ellis performs at Slammin', Fri/10, Throckmorton Theater, Mill Valley. (415) 383-9600. Dave Ellis plays at the Narada Michael Walden Foundation's Holiday Jam and Auction, Dec. 17, 7 Mill Valley Community Center, Mill Valley. For more information go to www.nmwfoundation.org. (Lee Hildebrand)