It seems like almost every (if not every) act that played at the Agora was recorded, whether the recording was subsequently broadcast on the radio or not. The Agora had a recording studio called Agency Recording that was situated in the same building, above the concert venue.
The reason, or one of the reasons, that you see so many CD reissues of Agora concerts is that unlike a lot of radio concerts which were mixed live to stereo, the shows at the Agora were recorded to 24-track two-inch multitrack tape and then properly mixed to stereo or quad after the fact. The only other entities I can think of that did this kind of thing wholesale were KBFH (now owned by Wolfgang's Vault) and the BBC, both of which apparently want so much money to license these recordings that even major labels are balking at it - the recent Black Sabbath box sets feature live material that WV should hold the multitrack masters for, but what's on the box sets is sourced from mp3 versions of the old radio broadcasts. Hank LoConti, who owned the Agora and Agency Recording not only kept all the multitrack master tapes, but has seemingly been agreeable when it comes to license these recordings for reissue, and as a result a
ton of them have been issued on CD in the last 25 years or so.
I think what sets the Agora recordings apart from a lot of other live recordings of the time is that because the recording equipment was permanently in place, and every recording was of the same venue, with the same mics and setup, there was a lot less of the 'unknown' factor at play. Live recordings are often bad because of unanticipated problems on the night, like bad acoustics, equipment malfunction, and so on, but because the Agora recordings were the same thing over and over, it was a much more controlled environment, almost like being in a studio, just with a 2000-strong crowd present. The other thing working in their favour was that because most of the bands didn't know they were being recorded (or if they did, they didn't have the pressure of it being a 'big deal' recording for an album release) they didn't have the same kind of "camera shyness" that a lot of artists have talked about when they know they're being recorded for a live album. The result is you get a much looser and more spontaneous atmosphere, and as a result they captured a lot of artists at their absolute peak.
Apparently when Hank LoConti died, all of the Agora ephemera, including all those master tapes (multitracks and mixed masters) became part of a huge archive at Case Western Reserve University, which is located not far from the original site of the venue. Ever since I discovered that the masters for these shows still exist a few years back, I thought it would be cool for D-V to do a series of live SACDs in surround, or double disc sets of a studio quad and a live album from the same period, but I think that the hurdles, both practical (getting a band to agree to it, finding tapes, making sure they're ok, mixing them, getting the band to OK the mix etc.) and financial are probably too huge for such a niche project.
There are a number of good articles about the Agora and Hank LoConti, that give you an idea of what the place was like and how they operated:
https://www.cleveland.com/entertainment/2014/07/legendary_cleveland_agora_club.html
https://clevelandhistorical.org/items/show/1
