Crackling sound while not playing anything.

Hi,

i’m running RASPI B with an audiophonics DAC and a sure Class D amplifier with volumio 1.5

As long as i don’t play any music file i hear a crackling sound through my loudspeakers, This crackling stops in the exact second when i start the playback of a music file, so i think its something pi related. It’s like a background noise while the sound output is idling.

Any idea how i can stop the pi from producing this background noise?

best regards
Kai