First, you should try out build 21 and see if that goes away. We made some improvements based on feedback in this thread that may improve your situation.
If it’s still happening, and you don’t get crackles when playing the same content in other software like Audirvana/JRiver/etc, please let me know so we can dig deeper (we’ve noticed some source material with crackles in the digital content, and it’s an easy test to just try it in another player).