Just uploaded version 0.11.0 to extras devel.

The most important new feature is an "interpolation" option.
This option allows you to choose the number of "samples" used for calculating the volume level.
The number of "samples" is two to the power of the "interpolation level".
Consequently, possible sample numbers are (theoretically, see below) 1, 2, 4, 8, ... , 1024 for the interpolation levels 0, 1, 2, 3, ... , 10.
Thereby, the sample number only defines a maximum value.
The actual number of samples used for calculation may in fact be (much) lower, depending on how much data was ready for processing.
As what I can tell, the settings 1 and 2 practically result in the same sample number of 4.

Currently, there is also some odd issue where the reported volume level may get "stuck" at about 60 dB.
In this situation higher values are still shown but the level does not fall beneath 60 dB.
Setting the interpolation level to another value or selecting a source should resolve this situation.

The second new feature is an option for restoring the default values in the settings dialog.

Furthermore, the changelog should now be properly updated such that you can also follow the changes in your package managers.
Thanks again to Mentalist Traceur for reporting the issue and to lcuk for pointing me into the right direction to get this solved.