Digital music

Playing digital music, there are several configurations possible.

There is always a streaming or transport device and a DAC (Digital Audio Converter) when playing digital music in the audio chain. The music is played from an audio server or the internet, like Spotify, Qobuz, or Tidal. It can also come from CD or SACD transport. 

Weiss Dac 501 8816.jpeg.  PS Audio Stellar Gold Dac 8799.jpeg

Weiss DAC501                                                                                            PS Audio Stellar Gold Dac

PS Audio PerfectWave SACD 8786.jpeg

PS Audio PerfectWave Transport  SACD

In this case, a transport can play CDs and SACDs but doesn't have a Dac like it used to have in the early days of CD players. 

So you need a separate DAC to play your CDs. 

Several components in a digital chain play digital music to an amplifier.
Components can be combined within one audio device. 

The digital chains with components.