It's a Monday night at an old movie theater that's been renovated into a nightclub in the heart of Mexico City. Rodrigo y Gabriela are on stage with their signature nylon-string acoustic guitars. Rodrigo Sanchez and Gabriela Quintero are from here. They started playing music together in Mexico City as teenagers in a thrash-metal band in the 1990s. But more than a decade ago, they went off to Europe to busk in the streets.