With one specific exception - stereo volume knobs often - virtually always - suffer from stereo imbalance, where the volume of the left and right channels are slightly different.
Some high-end amplifiers offer a relay based volume system where the knob simply switches resistors in and out of the audio path using relays to adjust the volume, and although this does result in "steps" of volume, it does mean the stereo balance is always perfect.
Some high-end amplifiers offer a relay based volume system where the knob simply switches resistors in and out of the audio path using relays to adjust the volume, and although this does result in "steps" of volume, it does mean the stereo balance is always perfect.