Yo La Tengo Pop bands don't get much more intellectual than Yo La Tengo, those hypnotic melodists from Hoboken, N.J., who produce some of the genre's most sophisticated music. So it was little surprise to hear singer-guitarist Ira Kaplan explain during the band's show Saturday at the 9:30 club that there had been "a theological discussion backstage" about a pressing question: "Does Passover always fall on Ash Wednesday?" (No, the audience seemed to conclude.)

A potential drawback of Yo La Tengo's thoughtful side is that the band can bog down in the sort of subdued sonic experimentation that tests an audience's patience. But on Saturday the trio kept its nearly two-hour set hopping with upbeat, crowd-pleasing tunes and a fascinating surprise twist.

The evening began ordinarily enough, with upbeat favorites like the band's shuffling 1997 hit "Autumn Sweater" and the delicate "Little Eyes" from the group's new release, "Summer Sun." Amplified drums gave a welcome extra kick to these songs' beats. And Kaplan's squealing, dissonant guitar solos -- played with the body English of a man wrestling a python -- always stopped short of self-indulgence.

But the fun really began with the surprise appearance of three members of the free-jazz Sun Ra Arkestra, with whom Yo La Tengo recorded an EP last year. These African American musicians, dressed in robes and fezlike hats of glittering red and gold, were a brilliant contrast to the nerdy-grad-student look of their Hoboken hosts. But their squawking horns and bright flutes avoided the peril of sounding like forced gimmickry, and added beautiful new dimensions to songs like "You Can Have It All" and "Little Red Honda."

The show achieved a state of controlled chaos when members of the opening act, Portastatic, crowded onstage for the funky, raucous Sun Ra classic "Nuclear War." It was a far cry from Yo La Tengo's typical sound, but for these deep thinkers, it was a typically clever musical idea.

-- Michael Crowley

Robert Hurst When Robert Hurst, the unassuming jazz bassist best known for his work with Wynton and Branford Marsalis, stepped to the fore as bandleader at Blues Alley on Saturday night, he balanced melodic invention, swing momentum and boppish velocity with sure-handed ease.

Fronting a quartet that generously featured pianist Mulgrew Miller, tenor saxophonist Ravi Coltrane and drummer Ali Jackson, Hurst casually navigated the group through a collection of tunes enhanced by his craft and imagination. His improvisations were so gracefully executed and neatly resolved that they occasionally took on an air of inevitability.

During an extended salute to Thelonious Monk, Hurst used a vigorously percussive attack to add a few wrinkles of his own to "Evidence" and "Monk's Dream." The latter was enlivened by Miller's evocative touch, which brought to mind the keyboard ties that link Monk to Duke Ellington. The pianist further distinguished himself during a reprise of "Farewell to Dogma," an impressionistic, self-penned ballad that built to a rhapsodic pitch while underscoring the post-bop interplay between Coltrane and Jackson. That was especially true during "Rousetabout," a tune Hurst composed for the late reedman (and Monk sideman) Charlie Rouse.

Before closing, Hurst invited Rob Randolph, a young trumpeter from Detroit, to join the band for a brief but spirited version of "Take the Coltrane" -- an apt and thoroughly crowd-pleasing finale.

-- Mike Joyce

The Iguanas Touring in support of "Plastic Silver 9 Volt Heart," arguably their best album in their 13-year career, the Iguanas rolled onto the Birchmere's Band Stand stage Friday and delivered a set of sax-driven Tex-Mex funk-and-roll that had the dancers twirling on the floor from the first note. The distinctive chemistry of the five players was on ample display as the New Orleans-based band showcased once again why it's Louisiana's best export since blackened redfish. The songs were silky and seductive, but propulsive and invigorating at the same time, and for the non-dancers there were intriguing dynamics amid the instrumentation to study. Second-line rhythms from drummer Doug Garrison and bassist Rene Coman supported coolly confident riffs from Derek Huston's tenor sax, while the guitars of Rod Hodges and Joe Cabral, who also played occasional button accordion, provided melodies that combined Mexican Ranchera with Americana.

Somehow it all worked, and it worked wonders. The older tunes, including the show's opener, "Para Donde Vas," "Boom Boom Boom" and "Benny's Cadillac," sat comfortably next to the new material, which was highlighted by the ridiculously catchy "Flame On," featuring an ascending Huston sax solo that threatened to levitate the dancers.

Alternating the swirling dance beats with sexy, sleek ballads, most of them sung in Spanish by Hodges and Cabral, the Iguanas laid claim to being the coolest lounge lizards north of the Orleans Parish border.

-- Buzz McClain

The Louisiana band the Iguanas kept dancers at the Birchmere Band Stand slithering Friday night with a silky, seductive Tex-Mex funk-and-roll.Yo La Tengo kept the subdued sonic experimentation in check during its performance Saturday at the 9:30 club.