Two pi audio spi cards, one input, one output, can this works

Putting my hardware together, and have issues to get both card to be recognized…
Though one is input (UGreen DABBoard), and the other output (HIFIBerry AMP2).
UGreen documentation mentions the DOUT and DIN can be connected (physically) to have DAB audio on the HIFIBerry.
But I like the software approach to play audio from files/streams.
Anyone any ideas?