The Absolute Ensemble might have been designed for the Barbican's genre-scrambling Only Connect series, and Frank Zappa's caustic, eccentric compositions gave them plenty to get steamed up about. Under the energetic semaphoring of conductor Kristjan Jarvi, the 20-piece "electro-acoustic" mini-orchestra whirled through their paces in music that took in blues, free jazz, atonalism, rock and mere sonic idiocy.

Even armed with a comprehensive set list, it wasn't easy to keep pace with the Ensemble's frenetic arrangements. Zappa's music revels in non sequiturs and grotesque juxtapositions, so every time you started to feel comfortable with a bit of blues or some rumbustious swing, it was merely a temporary respite before the band lurched off to somewhere you barely knew existed.

Jarvi is a shrewd, dynamic conductor, and under his jabbing arms and frantic body-language the Ensemble handled their abrupt changes of tone and tempo with aplomb. They made it sound as if nothing could be more conventional than to leap from mariachi stomp to pseudo-baroque string passages, sampling some cop-show theme music en route.

However, two hours of this stuff began to expose a few limitations in Zappa's compositional palette. Eclecticism? A fine thing, but maybe not as an end in itself. Irony? Of course, but if the irony pedal is permanently pressed to the floor, you start to wonder if you're a parody of an audience witnessing an elaborate pastiche.

Added Zappa-thenticity was supposedly imparted by the presence of Napoleon Murphy Brock on vocals, sax and pantomime costumes. Brock used to play with Zappa; somewhere along the line he acquired the notion that his crude slapstick and silly voices are in some way amusing. There was better value from the triple-DJs of the X-ecutioners, whose synchronised scratching lent a harsh urban edge to the likes of Muffin Man. Overall, a show that was intermittently gripping, sometimes irritating.