Something like this you can click on any part of it to move it. It much less fiddly and it gives you the value as well as a visual representation of where its at (you could couple this with a colour scale on the dial). The white bar above shows you where the value is in the available range and can be dragged for large adjustments.
Finally lets put some logic in the modifier and arrow keys.
Shift drag, shift arrow = 5x standard
ctrl drag, ctrl arrow .5x standard
Arrow keys raise value by the smallest increment available, not by a standardised increment. If you want coarser control bring alt into play, so that ctrl-alt arrow qives you 10 or 20x smallest increment.
However you need to minimise people moving from mouse to keyboard. So get them modifier keys working with the mouse. Current system is s mess: I have to use my mouse to click on the value to change value by 1 increment.