I get volume control clicking, If I pause the music, then select the on screen volume control and crank it up and down, I can here a corresponding slight noise in the earphones. Curiously, a similar noise is also present when using the hardware buttons, but only in the volume range of 60-80. I'm using z5s, with high gain selected. I'm pretty sure I've heard this on the Ety's as well. However, the sound is not present from the unit itself and unless the music is particularly quiet, I don't hear it in everyday use. I get the odd relay click even when the unit is doing nothing, but I live in a very quiet house in the middle of nowhere.