John Lennon gave the marching orders long ago -- Imagine. For his part, veteran concert promoter Rick Bowen imagined a rock concert like no other: Led Zeppelin and Pink Floyd playing together on one stage, Jimi Hendrix, Janis Joplin and other legends performing with the benefit of today’s state-of-the-art lighting and sound. The elusive tribal feeling, unique to classic rock concerts, recreated for a whole new generation. Well, Imagine no more. “Flashback – the Classic Rock Experience,” featuring the Mystic Orchestra, is about to storm the concert arenas of America – kicking off August 27 at the Civic Center in Mobile, Alabama.