Chamber music thrives in San Diego County largely because the La Jolla Music Society, Mainly Mozart and the universities import it in large quantities. But chamber music regularly performed by local musicians remains the exception. Maybe with string quartets such as Emerson, Calder, and Pacifica making such regular visits, local string players figure, “Why bother?” We have two flutists to thank for the popular, well-attended chamber series that do engage local musicians. For the last five seasons, Demarre McGill, the former Principal Flute of the San Diego Symphony, and his partner violinist Kate Hatmaker have cornered the contemporary music niche…