Three directions for the knob aesthetic, each shown statically at 0% / 33% / 66% / 100% and as a draggable instance below. Pick one and the rest of the surfaces (faders, sequencers, piano roll) align to that language.
Radial gradient, perimeter ridges, specular highlight from top-left, drop shadow. Reads as a real photographed knob. Premium but heavier; can compete visually with the rest of the UI.
Crisp 2D shapes, no fake depth. Bold accent arc, dot indicator on the perimeter, short tick from center. Reads like a Teenage Engineering OP-1 or a clean diagram. Quietest of the three.
Outline-only with strong glow. The accent arc and indicator both bleed light. Soft inner radial gradient. Synthwave / vacuum-tube feel. Brightest, most "instrument" — but the glow can be fatiguing en masse.