General Answer: The volume control circuits in the No.585 have been designed to provide exceptionally high levels of accuracy and linearity, and have been tuned to provide the best possible listening experience. You may hear small clicking sounds when quickly adjusting the volume control during periods of silence – this is normal when there is no input signal. The sounds are greatly diminished under normal use when listening to active audio sources. Detailed technical explanation: The volume control in the №585 is built around a circuit architecture called an R-2R ladder, a highly accurate device. The R-2R ladder in the №585 is based on an R of 1000 ohms, which is smaller by a factor of 10-100 than most potentiometer-based volume controls. The result is a nearly constant bandwidth, from the lowest volume setting to the highest, of greater than 400 kHz, more than an order of magnitude above the upper limit of human hearing. Because the resistance value in the R-2R ladder is so small, and because all DC blocking capacitors have been eliminated from the signal path of the №585, the few micro volts present on the input and output stages can give rise to extremely small but measurable DC currents flowing in the R-2R ladder. When the user adjusts the volume setting, the miniscule changes in DC current flowing from the ladder into the output stage occasionally can be perceived as small clicks, typically audible only under extremely quiet listening conditions.