it is true that the UBook’s speakers are not so powerful. There is a way to increase the loundness of the sound they produce as well as to improve their overall quality.
The solution is to open and adjust the sliders in the Realtek Audio Console app, that is installed as a part of the sound drivers in the system.
Anyone can adjust the sliders by its own preference, below I present what in my opinion sounds the best (especially when using earbuds):
The adjustments for improving sound quality:
To boost the volume, you need to move each slider up by the same number of points (in my adjustments, it is by 6 points) so the curve is remained.
This increased the volume by 19dB (I checked with the Volume meter).