Noisy when dynamic

[dude2010]

My setup is

mac mini 2011 -> W4S dac 2 -> Preamp -> Poweramp

 

When I'm listening to dynamic soundtracks, that has a fully 0dB signal, I get these electrically sounding sparks in the signal. Like a digital oversteer. I checked every volume control (actually they are all fixed due to the DAC) and nothing is above 100%

 

What is this?? Help!