I've seen a lot of talk in 3D printing circles about using "smoothers" to reduce artefacts caused by the vibration of stepper motors. Here, for example, and here's a site claiming they "also protect against induction voltages in the unpowered state of the driver". To my mind that's sounding a lot like the psuedo-scientific nonsense you get on Hi-Fi forums.
Basically the smoothers are two diodes wired anode to cathode in series with each pole of the motor. Apart from a voltage drop I can't see how they would effect the motor at all.
Is this based on physics, or just a way to sell overpriced