Comment by tavavex

Some of the music production UIs seem to feature huge grids of knobs, a pop-up slider would inherently obscure some of the adjacent knobs in some way, requiring you to move the cursor away or click somewhere else to dismiss it. It would create friction if you needed to do quick adjustments across a row or column of knobs.

I think the best compromise is something that's already very similar to knobs - a "draggable text field". Different software styles this element differently, but the essence is that it's a number, where you can either click and type a new value in, or hold the mouse on the field and drag it left or right to drag through the different values. You can find this in some video and 3D editors. Sometimes these elements are styled to have arrows on the sides of the numeric value to suggest the dragging behavior.