ST uses a relay-based analog stepped attenuator volume control design. An absolute value encoder at the remote transmits I2C code to the rack unit telling the relays when to change state. If the firmware detects any missed steps it places the unit into Dim to prevent the possibility of a blast of loud volume. Missed steps occur when a) the encoder contacts encounter wear (being an electromechanical device this is a fact of life,) or when b) the encoder is spun at a rate where it can’t track every step. Think of it like steering your car – if you jack the wheel back and forth like it is a joystick the performance will be a bit rough. If a large instantaneous jump in volume is needed for some reason employ the Dim button.