What is the scale of the volume slider?

I noticed on my Pi today (with Hifiberry Digi+, SqueezeLite ) that the volume slider affects the volume mostly at the end of the volume scale. Most positions of the slider are quite silent and at the end it gets loud very fast.
I tested afterwards on my internal MacBook Pro speakers and had the impression it is the other way around. There is a small range where the volume increases quite fast and then a big range in the volume slider where there is just less increase of volume.

Are there differences in the volume levelling between different devices and is the volume level scale linear or logarithmic?

Don’t know, but that would be a concern.

In addition, I have raised to @mike my concern that the slider is too sensitive. A slider is not an ideal user interface for this purpose. (The buttons used for Meridian gear is worse.)

I recommend a slow-geared roller like iOS uses for many purposes, like setting the timer in the clock app.