with a very basic /etc/asound.conf
pcm.!default {
type hw
card 1
}
ctl.!default {
type hw
card 1
}
I was able to get some sound out of my Rock Pi S. I connected headphones to GND, PIN 25 and PIN 26… BUT: I only got sound on one ear. I switched PIN 25 and 26 and got sound on the other ear so it not broken headphones.