Captain Beyond's eponymous first album was one of the prizes of my vinyl collection, and not just because of its way-cool holographic cover. I loved this album and wore out the grooves on it; at the time, I was heavily into prog rock, and these guys were inventive and had really superb musicianship. The album actually sounds better than this live performance, and I couldn't find the best song sequence (Side 2's "Thousand Days of Yesterdays," which you can hear here). Still, you get the idea.
Captain Beyond was actually a kind of second-tier supergroup. Rod Evans, the lead singer, had been Deep Purple's original lead singer (that was him singing "Hush"); drummer Bobby Caldwell was almost legendary at the time after his stint in Johnny Winter's band; and the bass player, Lee Dorman, and guitarist, Larry "Rhino" Rheinhardt, were veterans of Iron Butterfly (Dorman was the bassist on "In-A-Gadda-Da-Vida").
Reportedly Rod Evans was so distraught over the tensions making their second album (which was mediocre) that he quit the music biz altogether and became a respiratory therapist.