Could all the issues of MCS/QuadQ be scanned and placed in the QQ library?
Audio mag did mention the MCS review subscription info, but I didn't subscribe.
IMHO, CD-4 reached its zenith with the JVC Mark 3 mastering system and the Technics auto F/B separation CD-4 decoder in some Technics receivers and matrix decoding was close to optimum with the 3 band QS variomatrix decoder.
I love these old DIY hobby publications and newsletters. I was part of a Timex Sinclair computer group that had something like this well into the Internet age. I think it finally petered out because the main people who were doing the publication got older and it was a dying cause by then anyway. I had some older issues that someone had gifted to me and in one there was a advert for a disk interface that this guy had designed himself and sold back in the 1980’s. I wrote to the address not knowing if the guy was still in the biz, or even if he was still alive. He wrote back and I bought one from him and he even threw in some merch from back in the day. I was probably his first customer in 10 years.