Since forming in 1997 Bay Area band Tin Hat has gone through a few changes. Originally called Tin Hat Trio, they dropped the “Trio” when founding member Rob Burger left in 2004, to be replaced by clarinetist Ben Goldberg and harpist Zeena Parkins. Since then Parkins has split and so has her replacement, multi-instrumentalist Ara Anderson. Through it all guitarist Mark Orton and violinist Carla Kihlstedt have remained constants, as has the group’s wide-open chamber-music aesthetic, which draws from classical, jazz, cabaret, tango, and pop with an erudite, elegant, and often experimental bent.