AOQ, I have read thus thread with great interest, and I understand completely your frustration with CD-4. I took the plunge in 1976 with the following equipment: the receiver I had was JCPenney unit (likely made for them by Panasonic) that had two matrix decoders and 2 4-Channel inputs for tape and aux. I connected a Fisher CD-4 demodulator (a clone of the JVC 4DD5) to it. My turntable was a Pioneer PL-10 that I had fitted with an AT AT 14Sa cartridge. From the beginning, I had variable results from the format. Some records played perfectly (Carly Simon No Secrets and Hotcakes) while others had inner groove issues (Roberta Flack Killing Me Softly) and then there is one that is unlistenable (Cat Steven's Greatest Hits,) on any CD-4 demodulator I have owned. I think that at least some issues are due to record pressing problems. Others are clearly the result of the format failing to reach maturity, IMO. In 1979, the JCPenney receiver blew its output stages and could not be repaired, so I was quad-less until I got on the internet in the early 90s when I bought a Panasonic Quad receiver and a Panasonic strain-gauge cartridge. CD-4 was awful on that unit, so I started searching for different gear, and got no results until eBay came along.
I won't bore you with all of the various Receivers and CD-4 demodulators I bought in my search. But in the early 2000s, I lucked into a nice Lafayette LR 5000 (likely made by Pioneer) that has a fairly decent demodulator along with a full logic SQ decoder. It's CD-4 performance is only marginally better than the Fisher demodulator. I still have it as a standby along with a JVC 4VR 5436 receiver which has an excellent CD-4 demodulator in it. Cat Steven's Greatest Hits is still unlistenable, however.
Fast-forward to 8 years ago: I was finally able to get my hands on a Sansui QRX-9001 fron QRXRestore, and that is when CD-4 started to improve for me. That receiver is the heart if my quad system. I'm using a KAB modded Technics SL 1200 Mk2 (Cardas rewire and before you ask, I with the tech an told him that the wiring had to be at 100,000 pF, which he agreed to do.) The cartridge I'm using is an Audio Technica VMH 750SH, and I am finally getting great sound on most of my CD-4 records. Last night I listened to Seals and Crofts Summer Breeze (it has a little background hiss because it got played with a standard elliptical stylus...
), Eric Clapton 451 Ocean Boulevard, and Judy Collins Colors of the Day. Summer Breeze and the Judy Collins I bought while I was still in college. The Eric Clapton is a used one I picked up for 10 bucks, it has a few scratches but demodulates flawlessly.
I could go on but I am tired of typing with my thumbs! Feel free to ask me anything you want. I promise to be briefer!