For years now it’s been obvious that the classical orchestral concert is in need of some rethinking for modern audiences. And no one has been more out in front of this issue than the S.F. Chamber Orchestra, which began its popularizing mission by giving all its concerts away for free. Its current music director, Ben Simon, has gone the full monty, trying out a variety of new ideas. Simon’s new venture, “You Gotta Hear This” at the Rrazz Room in S.F. is an expansion on his original ideas.