[Solved] audio via DP on Asus z97-a + GTX980

[asheenlevrai]

As personal "bookmarks" (for future reference) I post these free solutions here:
1) SoundSiphon:
Demo version is free forever and apparently does the job

2) (controls via app or keyboard shortcuts, not via dedicated apple keyboard keys: F10-F12)
https://www.tonymacx86.com/threads/a-small-utility-to-adjust-hdmi-and-displayport-volume.229156/
fork1 (Bluejamesbond) : https://github.com/bluejamesbond/MonitorControl.OSX
fork2 (Tyilo) : https://github.com/Tyilo/MonitorControl.OSX

3) https://github.com/the0neyouseek/MonitorControl

Another fork that looks very promising:

Control your external monitor brightness, contrast or volume directly from a menulet or with keyboard shortcuts :
...
You can use Karabiner Elements to use the default mac key (F1, F2 for brightness and F10, F11, F12 for volume) with this set of custom rules : Karabiner rules for MonitorControl
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Bonus: Using keyboard shortcuts display the native osd