Reply to Audio pops & crackles with s4 & MacBook

Did anyone else encounter this problem?

It doesn't matter if I use the s4 with Traktor or just as a soundcard for my MacBookPro, every two-three minutes or so there is some tiny pops coming from the speakers. They're not very loud, just some short high frequency cracks.. I checked with headphones as well to see if it's the speakers - nope, same story.

It's not a performance problem of my laptop, so I have the feeling it is some hardware error on the s4. Also, it happens with or without the electricity supply for the s4 plugged in.

Also, the s4 causes a massive pop when it's turned on, so that I always make sure that my (active) speakers are turned off before the s4 is turned on.

In case that the voltage plays a role, I'm located in Europe (Germany)