I don’t think it was specifically THX. I think it was a minimum quality of projection and audio. For instance my hometown theater had to upgrade their speaker system and installed a number of new speakers for better surround sound. Before TPM it was screening The Matrix which I had seen there a few times. And on the opening night of TPM I went to the final screening of The Matrix with the upgraded system and it was definitely a noticeable uptick in quality. And according to the quote I posted above it sounds like this was something that was universally required for any theater wanting to screen TPM. I’m just struggling to find much info about it other than the article above (partly because of the recent re-release of TPM spamming the internet with articles about the 2024 release)