SHUT UP AND RAP: The Opera House event was Gala, all right, but it could have used more vocals.

There must have been some people in the audience at the Opera House Sunday besides me who breathed a sigh of relief when, after the first song, Beastie Boy Adam “Adrock” Horovitz started yelling in his distinctive nasal mewl, “Back to the back to the beat, y’all!” The Beasties are working their new sorta-okay instrumental CD, The Mix-Up (Capitol), and the Opera House show had been advertised as an all-instrumental “Gala Event” and 43rd birthday party for Beastie Adam “MCA” Yauch, with instructions to “dress to impress.” The “Gala Event” was to be followed by a business-as-usual mix of hip-hop, hardcore, and jams at Bank of America Pavilion on Monday.

At the Opera House, after a bowed-bass intro (!) by Yauch, the Boys — with the supporting cast of turntablist Mix Master Mike, drummer/percussionist Alfredo Ortiz, and keyboardist “Money Mark” Nishita — kicked in with the hard funk, which sounded fine. And the sold-out house seemed happy to hear whatever the Beasties wanted to dish. But that second tune — “Live at P.J.’s” — held out hope for the rest of us. The instrumentals offered pleasant-enough grooves, dirty fuzz bass from Yauch, and wah-wah guitar from Horovitz. It was Nishita’s organ licks and Ortiz’s breaks on timbales and congas that provided the highlights, however. And the stage set of Calder-esque mobile projection screens afforded plenty of color. There was hardcore old and new (“Tough Guy,” check). But it was those classic Beastie raps scattered throughout the set and into the encore — “P.J.’s,” “Jimmy James,” “Gratitude,” “So Wath’cha Want,” “Sabotage” — that gave the night its juice. And when Yauch, Horovitz, and drummer Mike Diamond jumped around stage unencumbered by instruments and shouted call-and-response riffs with Mix Master Mike on “Three MCs and One DJ,” it was downright thrilling — something you couldn’t say about any of the instrumentals.