The blistering pop of guitar strings, a thundering ground beat, and an audience clapping in three different rhythms — this is a night with Mexican guitar heroes Rodrigo y Gabriela.

Fans at the Tower Theater Saturday night watched as a two-headed monster — the genre-breaking acoustic duo of Rodrigo Sanchez and Gabriela Quintero — joined forces with new musical allies, six members of the Cuban ensemble C.U.B.A., a collaborator on the duo's most recent album, Area 52.

With deft backing from the band, Rodrigo drilled out one mini-gun melody after another and Gabriela beat rapid rhythms on the wood and strings of her guitar, her hand shaking like a flame.

Launching first into "Santo Domingo," the black-clad musicians built on a riff that was part folk, part speed metal. That composition, like the others performed with the Cuban band, was a reworked version of an older track. The guitar duo made its vivid declarations; C.U.B.A. added exclamation points.

The virtuosic show captured the next turn in an evolution. The guitarists rerouted their careers a decade ago when they quit their metal band and moved to Ireland. Since then, they've been swallowing up new sounds. Contrary to popular assumptions, they don't do flamenco. But the Tower audience witnessed hints of everything from metallic riffage and acid-rock moans to ska and toothy acoustic dance music.

Playing with a rhythm section, horns, and a backup guitarist allowed the duo a bit more freedom than usual. Gabriela grinned widely and bounced across the stage to the big beats. The two split up and played alongside the band members.

They had a fiery partner in strings with bassist Alfredo Hechavarria, who took a solo against a tight drumbeat, scatting every note he played. The other members took turns in the spotlight as well.

But Rodrigo y Gabriela won it back, with neat leads and rhythms and outright shredding on songs like "Ixtapa" and "Tamacun." And when the band took a break, the guitarists reignited the dynamic that made their reputation.

Contact Matt Huston at 267-872-9207 or mhuston@philly.com.