Matt Haimovitz & Uccello take the stage at SXSW - CNN

When Matt Haimovitz and Uccello take the stage, they sometimes work their cellos more like guitars, or drums, or or any other instrument that might be chucked across the room in a fit of rock-rage musical passion. "I'd been wanting to play South by Southwest for a long time," said Haimovitz, a professor at McGill University's Schulich School of Music in Montreal.