I have no idea what is being discussed in this Z17.3 thread of late, seems to have become a German language thread. I personally think it would be beneficial to all, if non-English posts were translated by the poster to English language, that way more members would feel encouraged to contribute and not skip over. There are now too many posts to be translated by anyone.
Anyhow, back to Z17.3. I have just created a Z17.3 Core USB and booted it. Sadly I could not get any Settings>Sound>Test Speakers to work.
For those that have been here for a while, you will know that has been a common issue for me to fight with each new ZOS version.
I guess I will keep using my trusty Z16.3 Core, which works well, for the time being. I know I am not alone still using Z16.3. I also know support will soon be coming to an end for that version. But it works!