I'm back. Here are some updates. The Sansui QRX-6001 died and no sound came out of it although it lights up. I replaced it with a Sansui QRX-7500 and had the same problems with CD-4 records as before. One thing that I did discover was, although new, the headshell I was using caused a hum in the system and that hum probably led to the demise of the QRX-6001. I put my Shure quad cart in a new headshell and the hum went away. Being an idler drive and having a huge Bodine motor powering my QRK turntable, there was just too much motor noise coming through. I ended up buying a new AudioTechnica AT-LP120-USB direct drive turntable with all the features you would expect in a good turntable and installed the quad cart in it. I was getting the same ticks, pops and surface noise with the new turntable hooked to my newly acquired QRX-7500 in the CD-4 mode. Although it sounded great, the QS quadralizer wasn't quite as good as the 6001.
The next saga, I acquired a Pioneer QX-949. Although the CD-4 demodulator was noticeably better than the Sansui's, I still get all the same surface and background noise, but not as bad as with the QXR's. As before and with the other two receivers, in the stereo mode, the sound is excellent.
Does anybody out there know if this is just the way CD-4 records are or is there something that I am doing wrong?
-Dan