I think it was around 1970 at Roosevelt Stadium in Jersey City, NJ. The stadium was located right on Newark Bay. We went to see Rod Stewart. The opening acts started playing in the afternoon.
Lynyrd Skynyrd did the first set and just knocked it out of the park (pun intended)! The crowd was blown away. We called them out for two encores. They were amazing. Then Ten Years After came out. Even Better! Alvin Lee was tearing it up with his guitar riffs. Two more encores. By then it was starting to get dark. I guess Stewart was pissed that we made him wait because he made us wait at least 1/2 an hour before he came out. By that time a stiff wind was coming off the bay and totally screwing up the sound. All we could hear was vocals and drums. People in the front started shouting things to that effect and Stewart warned them that if they didn't stop, he would. No one in the band or crew seemed to understand that we wanted someone to come and adjust the sound mix. I don't know if it ever got straightened out. We left.
The same year we went to see The Moody Blues at Drew or Fairleigh Dickinson University. We thought we'd be going to an auditorium. Nope. It was just a large classroom with a 'stage' that was about one foot higher than the floor. The opening act was Mott The Hoople and they were great. In between sets we could just walk up the the band and chat. It was great and Mott was every bit as good as the Moodys.