For optimum sound quality, we recommend taking advantage of the internal DACs of the CXN.
To ensure this, the CXC needs to be connected to the CXN via S/PDIF, and then the CXN connected to the CXA-80 via balanced XLR (unbalanced RCA cables for the CXA-60).
This then means you would have to select the digital input on the CXN before any sound is produced by the CXA.
For a quicker and more convenient connection, you can connect the CXC directly to the CXA via TOSLINK optical cable.
For the best of both worlds, you can combine both of these connections for different listening occasions. The S/PDIF and TOSLINK optical outputs work simultaneously on the CXC, so you could use the direct connection to the CXA for quick convenient listening, and use the S/PDIF connection to the CXN for optimum performance and quality.