It entirely depends what sort of amplifier/receiver you are connecting to;
If your amp/receiver can handle DSD or PCM over HDMI, then this is the simplest way to connect. This way, the CXU will simply be acting as a transport and the amp will be doing the decoding, so the audio quality will depend largely on the quality of the amp/receiver.
If your amp/receiver can't handle HDMI audio, or you want the CXU to do the decoding (so that the sound quality is more the result of the Blu-ray player than the amp) then you can connect the analogue multi-channel outputs into the amplifiers multi-channel direct input.
You will only get the benefit of the CXU's Wolfson DACs and ATF upsampling by using the analogue multi-channel outputs.