SPDIF questions

[gen2thomas]

Summary:
Asus does not provide S/PDIF on the S/PDIF pad. Standard conform connectivity involves an adaptation network of the, what we have is just a TTL raw signal and nothing more. The board does not have the needed HF design to provide proper connectivity. Just connecting an RCA jack will have an inferior sound quality as much of the bit information will very likely not be transmitted in a way that a receiver will decode it in a meaningful way. Jitter is preprogrammed. The voltages provided are far above the range of S/PDIF and very likely destroys a receiver.

Asus information on this and hardware documentation is literally non-existent.
How should tinkering work with such a baseline?

Thank you very much for your work - this turned me to the right direction - using an toslink adapter. See this post in armbian forum: "https: //forum.armbian.com/topic/4807-tinker-board-sound/?do=findComment&comment=72866"