ES-8388 Analog Audio Works At Fractional Volume (a possible solution)
The issue of no ES-8388 analog audio output has been dragging on for months, and in all three kernel flavors (vendor, mainline, edge).
I've discovered, at least with the latest edge kernel (as of Armbian 25.8.1 today), that the audio through the ES-8388 IS actually coming out, and the sound is clear. It's just that the volume that can be heard is extremely low and barely perceptible if all volume controls are maxed out and the audio file itself is at full volume range.
This Bug Is From The Kernel / Driver Development Before It Gets To Armbian
This is not new, I'd discovered this earlier and on other operating systems as well. So I know the issue is coming from the kernel / driver development, before it gets to Armbian.
My Thought: The Audio Is Bit-Shifted by 7 or 8 bits
I would venture an educated guess that the audio is 1/128 or 1/256 the correct levels (i.e. bit-shifted by 7 or 8 bits).
This could be caused by, for example, a 24-bit audio integer value being copied into a 32-bit integer buffer without bit-shifting by 8 bits to align the MSBs (most significant bytes). The sign bit could be why it may be 7 instead of 8.
The Easy Fix (for someone familiar w/ the source code)
If this is the case, then someone familiar with the source code, who knows where this is - it would be a real simple fix. On Fedora KDE, I was able to crank up the volume even beyond max settings to try to make it louder, and it got clamped instead. My thought is that this confirms that the issue is the final mix is going to the device, which would make sense.