Over the course of 20 years and eight albums, the subdudes have quietly become one of America’s national music treasures. The New Orleans-formed group is a living encapsulation of American music, a vibrant cauldron of sounds that stirs together meaty grooves and jazzy dynamics, souful R&B swagger, easy vocal harmonies, cheeky rock ‘n’ roll attitude and folky social consciousness — not to mention some of the sharpest musicianship and ensemble playing you’ll ever hear from any five musicians. It’s tight enough to be loose, but never gratuitously sloppy.