I just started up a new HP Pavilion x360 14m-dw0023dx, and I also find that this Realtek Audio system does not provide for the Stereo Mix option that is so necessary for video conferencing if you need to play sound/music from within your computer. I tried the Realtek driver link you provided above, but got a message that it is not supported on this OS -- Windows 10 Home, version 1909, build 18363.1110, installed 10/10/2020 (today). I had also tried another Realtek driver link that you provided in another message, that being sp77787. It did not do anything. The sound drivers listed in the Device Manager are: two listings for Intel SST, both of which are driver 10.24.0.3694 (3/13/2020), and Realtek Audio 6.0.8934.1 (4/14/2020). It seems that no matter what driver other drivers I try to install, these three listings in the Device Manager under Sounds do not change. (I had an Intel Audio Display, but had deleted it along with all of them to try to get updated drivers with a restart. That one didn't come back with the restart.)
By the way, my HP Pavilion 360 11 inch from 2016 lost its Stereo Mix to a Windows Update in June. I was able to do a restore to get it back and have been delaying updates ever since, hoping that there would be a fix for this problem. I did try installing that driver from HP support for that model, but it did not work on the new one anymore than the others did.
I am still in need of either a Stereo Mix Realtek Audio driver or option. Or some other kind of work around that allows for using the internal speakers for INPUT instead of the microphone for video conferencing. The Virtual Cable third party option did not work, since it function like a microphone with a condenser mic and only had auto volume control.
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