In a 'normal' CD player, the CD's digital information is read and passed through a DAC (Digital to Analogue Converter) inside the CD player. The resulting analogue signal is then output to the amplifier, usually via an RCA connection.
The CXC is a CD Transport. This means that the CXC plays the CD and extracts the digital information from the CD disc and outputs it digitally, via S/PDIF Coaxial or Toslink connection.
As we use a high-quality ESS Sabre DAC inside our CX Series amplifiers (CXA61 and CXA81), we recommend outputting a digital signal from the CD Transport and to allow the digital to analogue conversion to take place in the amplifier instead.