Logarithmic volume scaling
From what I can see, you're using just a normal linear scale for the volume. The difference in perceived volume above 50% is barely distinguishable now.
Human ear perceives volume logarithmically, so I guess, the best option is to go with it. That way lower volumes can be actually more silent and the difference between 100% and 90% would be distinguishable now.
Also, in my opinion the step
value should be removed from the volume slider. There are situations that I'd want to set the volume pretty low and the step
value doesn't help with that at all. I have to pause the music to hear what's someone saying to me but I'd rather just turn it down to the point that I could hear both music and the person I'm speaking with.