I just found this program today and for some music capturing from the web I have the same issue. I suspect it is because the audio input is to high. I was looking on this forum to see if it is normal for SoundTap to lock your system volume on max because the OS X version is doing that for me when the program is running. If the audio stream I am trying to capture has a volume control I've been able to eliminate the crackling but some streaming audio doesn't provide any control other than play and pause and those always crackle.