While bands like the Chemical Brothers and Prodigy mix rock and techno to create their own versions of electronica, bands like Roni Size and his Reprazent crew are mixing it all up -- soul, hip-hop, dub, jazz, and drum n' bass -- to create a more forward-looking musical hybrid. Size is the next superstar outta Bristol, following the smash successes of Portishead, Tricky and Massive Attack. But unlike those bands, Size is no sultry trip-hop groovester; his music reaches into the deeper, darker and fiercer realms of jungle. It's simultaneously more aggressive and more danceable.

At his first live show in San Francisco, Size combined live instruments and electronically sampled beats so seamlessly that it was impossible to tell who was doing what. The full band, known as Reprazent, is really a supergroup of Bristol characters who play individually and with other bands. Their interplay, improvised as well as digitally controlled, made for a riveting show best described as organized confusion.

As lights flashed furiously, the group appeared from behind a cloud of smoke. No men with guitars or mic stands here, this was an industrial arsenal of electronic machinery: DJ Krust, DJ Die, Suv and Size surrounded themselves with keyboards and monitors at center stage. On the periphery were percussionist Clive Deemer and bassist Si John (straddling astand-up bass to start the evening). Up front and leading the band were vocalists Onallee and MC Dynamite, who many in the audience undoubtedly assumed was Size, since Size remained hidden by his devices and never once came out to greet his fans.

The show opened with "Morse Code," a track from last year's heralded CD, New Forms. Dynamite, wearing a skull cap and pullover jacket, immediately won over the crowd, gesturing and strutting across the stage -- an engaging rapper preaching to the converted (the show easily sold-out). At his side, Onallee danced passionately, smiling and breaking into boxer-like moves whenever the beats consumed her.

Hard as it was to discern exactly when one song stopped and another started, it was clear when Size's hit, "Brown Paper Bag," came on. Onallee howled her "eeeagh" with particular gusto, setting off a thunderous wave of beats and manic dancing. Attentive viewers could see Size's head bobbing up and down to the beat, immersed in his aural collage.

After a few more songs ("Share the Fall," "Heroes," Watching Windows"), the band's more soulful side emerged. Onallee's sweet, silky voice carried the tunes while string-like samples and synthesized melodies played behind her. Sometimes, she'd work the stage with MC Dynamite, dancing with her cohort and motioning at the audience. At other times, she stood still, digital diva style.

The climax came during the extended encore jam of "Brown Paper Bag," a less-structured version of the hit. Dynamite offered up some improvised scatting, while Size threw in spacey synth lines and alternated the pace using slow & groovy bass lines and acceleratedbreakbeats. It was a tad longer (and duller) than the previous string of songs, but dove more deeply into theme variations and dub-like experimentation.

For a band that essentially does the electronica thing, Size/Reprazent show off many a cool new move. Unlike so many others, they combine live elements with samples, juggle music styles, and transfer that musical energy into a thoroughly gripping performance. While the live show didn't offer the eclecticism of the CD, it certainly never got predictable. More important, Size's vast digital soul displays enough musical complexity to satisfy hyper-attentive critical ears -- with enough kick for those who just wanna dance till theydrop.