Interesting sentences from the CS Port website: "Servo noise is eliminated by open control that does not apply a servo. In addition, a highly accurate voltage is supplied to the motor without fluctuation based on a crystal oscillator with high frequency accuracy."
Seems to me that the crystal oscillator per se is a servo mechanism, albeit acting further back in the process of driving the motor, at the PS level. Also, the phrase "servo noise" reminds me of the humorous aphorism, "when did you stop beating your wife?" In both cases, guilt is assumed.