The codes have been updated with a lot of bugs fixed.
Basically I've overhauled the setup instruction and it's now reproducible with a fresh-installed Armbian Bionic 5.90. (I believe.)
I've also added some information about enabling the on-board Audio output.
Well, Since it's almost automatically configured by pulseaudio, what we have to do is:
# Enable `analog-codec` overlay$ sudo armbian-config # [System - Hardware] or sudo vi /boot/armbianEnv.txt
# Create the simple ALSA config$ cat - | sudo tee /etc/asound.conf
# Ctrl + D
# Install pulseaudio (the daemon will be launched automatically when Xorg starts )$ sudo apt install pulseaudio pulseaudio-utils pavucontrol
# Configure the audio settings as you like$ DISPLAY=:1 pavucontrol # Launch pavucontrol in a VNC display at :1.$ alsamixer