You can connect the optical input of WiiM Pro from another audio source such as Vinyl player, TV or PC and transmit it to another WiiM attached speakers via WiFi or Ethernet as long as they stay in the same network. Since the audio is transmitted digitally and the best audio quality is preserved. Regarding the use of optical out, you can connect WiiM Pro to your DAC, AMP or powered speaker via this interface and use the WiiM Pro as your primary media source. Again, it's able to stream the Hi-Res audio up to 192 kHz/24-bit.