Pretty much any DAW or audio editor will let you insert markers on the fly during playback, and you can reposition them with sample accuracy. Off the top: Reaper, Ableton Live, Wavelab, Nuendo, ProTools, Adobe Audition, probably Audacity. Some programs make working with markers a pleasure, others are more awkward.
Set yourself up a master group channel in Cubase
Route everything into this before routing that to your output devices channel
The master group channel now becomes the max level output of your mix, and the output device channel can be used to control actual volume
Standard practice, whatever type of audio interface you have
I finally found solution for this that works and it's free (open source). You can even hear the audio source from three different audio outputs.
My hardware setup:
PC with Realtek Audio (Windows 10)
Two LG Displays connected with HDMI
What I wanted is that the audio will come out from both displays. Unfortunately Windows 10/Realtek Stereo Mix "...