The Control Bus allows any compatible Cambridge products to synchronise when powering up the units. See the following diagrams when connecting the CXA using the provided Control Bus cable.
Another added feature with this Control Bus is the use of the StreamMagic app. You can use the StreamMagic app to control the CXA via the CXN.
StreamMagic app (via CXN)
When using the app to turn the CXN on/off, this will also turn the CXA on/off. The app can also be used to control the volume of the CXA. Connect the CXN control bus out to CXA in. For more information, see the CXN manual.

CXA with CXC
When turning the CXA on/off, this will also turn the CXC on/off. Connect the CXA control bus out to CXC in.

CXA with CXN
Note: Without using the StreamMagic app to control the CXA.
When turning the CXA on/off, this will also turn the CXN on/off. Connect the CXA control bus out to CXN in.

CXA with CXN and CXC
When turning the CXN on/off, this will turn the CXA and CXC on/off.
With all three CX devices, connect the CXN Control Bus out to CXA Control Bus in. Then connect the CXA Control Bus out to CXC Control Bus in.
Note: Do not loop back from the CXC Control Bus out to the CXN Control Bus in.
Control Bus will also need to be enabled and set to 'Amplifier' within the CXN device settings in the StreamMagic app, once the app has been connected to the CXN.

Note: The CXA, CXN and CXC all have an Auto Power Down (APD) function. If APD is enabled and one of the devices is switched on but inactive, the device will automatically power down after the selected APD time. This will then switch off all the other connected devices, due to the Control Bus connection.
If you don't want the devices to go into standby automatically, we would recommend disabling the APD feature on each device.