I heard it at Busch Stadium in 1989 for The Who and I was shocked at how good it was. I wasn’t in the business at the time. The bass solos on My Generation were so present and so clear, the whole thing was just stunning.
Side note: I was in their unassuming Dallas shop and was shown a dbx compressor with the comment “that right there will drive every amp rack we own”.
I heard it with Phil Collins at the Miami Arena in 1993 if I remember correctly. I was so impressed I started to look for info on it. One employee of a loudspeaker system manufacturer told me at the time that the boxes were not the same and sent me a picture they had at their headquarters of it. Apparently they studied the Prism for years.