DiegoHG:
As you said I can connect CK pin to Digital #13 , the SDO pin to Digital #12 ,the SDI pin to Digital #11. But this only for one amplifier. How do I do it with all the others?
You will need to make some sort of wiring harness. Or temporarily use a solderless breadboard to make the connections. When you know it works get out your soldering iron.
But my SD-card also needs to be connected to the 5v pin. How can I use both if I have only a 5v pin?
Likewise.
...R