John Barleycorn Must Die, Traffic
I decided to start with this album because it seemed to me that would not be a huge departure from the music of The Grateful Dead, Parker and Diego's favorite band. I later learned that Dead and Company actually play Dear Mr. Fantasy in concert and that Parker had already gone down this path.
Steve Winwood was one of the members of the band. He was known at the time as "the prodigal son of british rock" since he was very prolific at a very young age. In 1969 he formed the supergroup Blind Faith with Eric Clapton then came back to record this album with Traffic. He had an amazing solo career after Traffic. His bandmates from Traffic Jim Capaldi and Dave Mason would also have relatively successful solo careers.
Most Traffic fans prefer Mr. Fantasy, but for me this album is their most sophisticated album and it starts to show more influence from Winwood's solo career. The album has a lot of jazz/blues fusion and improvisation, showing less structure than their previous albums.