"I have read a report that the volume knob in the K1 or K1-XE ( I don’t remember clearly about the model), might cause some small noise if the user do not turn the volume up and down often."
faust,
I think you misunderstood the report. The volume control itself makes noise when turned up of down, but this complex volume control was created just to ensure maximum elimination of any noise whatsoever in the audio circuit and makes the K-1/K-1xe one of the quietist preamps ever.
I have owned the K-1xe for seven years and never had any noise issues whatsoever with the volume control.
Best to you faust,
Dave