I've read of some music recorded to enhance the processing the Circle Surround performs but it is not an encode-decode system as the various matrix 70's quad formats are. CS is basically an audio processor designed to work ona stereo source.
Actually, I think you are refering to the SRS system, which among other things was included on many early stereo televisions to enhance the separation. My old Sony XBR has it. That was a two-in two-out system, but Circle Surround is a true matrix 5.1 channel format ... encode/decode. It is somewhat compatible with Dolby Pro-Logic, in that it is quite suitable for movie playback, but MUCH better with music because it allows full freqency range, and two-channel rear sound. There have been many CS CD releases ... all of the Telarc CDs that are marked Surround Sound are Circle Surround encoded as I understand. I have a Rocktron 5.2.5 CS decoder and it is pretty amazing. CS is also included in receivers from Marantz, Kenwood and others, and in some high-end pre-pros like the Theta Casablanca. Cheers, Mike.