Control sushi on boards?

Thank you very much, Gustav!
Regarding the hat I am not quite sure, because I used
the DAC2 Pro, which might be slightly differ from the
DAC Pro.
I already ordered a HiFiBerry DAC+ ADC Pro,
to ensure, that I will be able to select a definetly matching hardware
for the hat.

The audio input and outputs are connected as you sayed.
(input to the 3.5mm jack).
I think,Stefanos post to my other question
could also be of importance:

Independent from that: maybe I could ask you:
on your page
https://elk-audio.github.io/elk-docs/html/documents
/getting_started_with_development_kit_elk_pi_hardware.html
there is the assembly of an “elkpi” hat displayed.
I could not find out where to order it. Do you still sell it?
In the video: https://www.youtube.com/watch?v=euB_fGGumZg
also seems to be a big board (ElkPi hat?).
Where could I buy it?
Thank you for your help!