New Orleans, the birthplace of funk and the preferred stomping grounds of jam band fans and followers of the freak philosophy, has a history of historic jam sessions that goes back more than a century. The influx of national touring bands amid the anything goes nature of Jazz Fest has added star power to many of these one-off lineups, but the newly formed Magnificent 7, put together by keyboardist John Gros using members of several top local bands, promises to be the headiest of these strange...