Khadas Tone1 board - activate coaxial sound output

I do not manage to get any sound output from by Tone1 board coaxial output. According to the product specs, the coaxial is bi-directional input/output.
How can I activate it in output mode? thanks

Hi Gasparov,
The current firmware of Tone1 only supports S/PDIF IN and does not support S/PDIF OUT now. We are collecting some info, and will make a update plan in the future.
Thanks for your feedback, Other Tone’s suggestions can also be reported here. Thank you.