Thanks for your reply. Yeah, I am already using the optical connection for my CD player. Analogue RCA connection was an alternative but it is inferior compared to digital connections, so I was looking for a way to use the HDMI connection.
You can upgrade to Nuprime CDT-8 Pro which has the I2S output on HDMI port, then the optical port can be used for TV
Okay. So the HDMI input is using a numprime custom protocol and isn't supposed to work any other products from other companies?
Quite a few manufacturers have implemented I2S on HDMI. But this is not an industry standard, so if a vendor introduces extra feature on the control pins, then there could be compatibility problem.

We use pin14 to indicate if the format is DSD.