I didn't know CSS was also available on CDs. CDs do have the SCMS (serial copy management system) that flips a bit in the S/P-DIF protocol. The audio data itself isn't changed, but a bit tells the target machine "only playback, do not record!".
In 1998, I designed the "Gemini", a copy-bit killer that removes this bit, but leaves all track start/stop information in the data stream. The device has become illegal a few years later, but "professional recorders" still have a menu item called "ignore copy-bit" - these aren't illegal, but they are a lot more expensive. There must be a different law for those who can afford the "professional" recorders...