I was there -- it was awesome!!! It was out there but now I'm here!
I recall the Yes concert was the first big name prog concert I ever went to.(I was 16 years old) Followed by Jethro Tull later in that year from memory.
I don't know if I can give you the real specifics of the night but I do recall how absolutely astounding it was. I also remember the glow of joints being fired up everywhere all around the hall which held 3000 people or so.
The opening was all in the dark with the whole hall in a dim red glow from all the joints....wow, the tinkling intro to CTtE fit the scene perfectly. Then a spot on RW with his waistlong white hair over the metallic shining cloak.
I think from then on I was in a mesmerised daze for the next hour or so!!!