I find the slider(s) very cumbersome to use. A landscape mode would probably help.
It’s really difficult to turn volume up/down just a little with the slider.
Maybe add an alternate method, something like a number with up/down controls, so could change volume in small increments. Either an addition to current UI or maybe an option to use slider or other mechanism. It would also be helpful to see the current volume level, so I can set it accordingly depending on what I’m listening to.