Live/Dead may not have been the first instance of a band refinancing their studio bills with a relatively inexpensive live release, but it may have been the most successful. The Grateful Dead — $180,000 in debt to Warner Bros. — jacked into the first 16-track mobile facility in early 1969. “We were after a serious, long composition, musically and then a recording of it,” said Jerry Garcia. The double-vinyl Live/Dead opens with a side-long “Dark Star,” explores the cosmos further in “St. Stephen” and “The Eleven,” continues with Ron “Pigpen” McKernan’s lascivious side-long take on Bobby “Blue” Bland’s “Turn on Your Love Light,” and brings it all back home with a Rev. Gary Davis blues followed by “Feedback” and an a cappella “And We Bid You Goodnight.” On the greatest advertisement for a band’s in-concert capabilities recorded to date, the Dead proved themselves both serious avant-gardists and impeccable roots revisionists — and spent the rest of their career reaffirming it onstage. Richard Gehr