The Grateful Dead, Live, no albums, just sound boards or audience tapes of actual concerts.
1970 was a very good year. Google “grateful dead archive by year” and listen to Feb 12, 1970 and September 19, 1970. The sheer quantity and quality of their work is sublime. Some of the best is for sale, which is fair, but you can listen to thousands of concerts for free. May 19, 1977 (Barton Hall) is a good concert for a free first listen, as are hundreds of others.
Phish - A Live One