Hey guys, I'm not experiencing the issue on either of two Windows 7 systems so I don't think the game itself is to blame. The fact that at least some of you experience the crackling only during the most intense sounds suggests that for some reason the game's or system's whole mix is too loud during those moments.

I can think of two possible reasons: the default volume settings of the game may be the maximum volume levels where there's no crackling and you guys may have turned the volume up in the options beyond that level. Another reason may be that you have some software amplify your whole system's audio mix. If the latter is the case I highly recommend you check whether you have some software installed that provides such features, some audio drivers come along with such stuff. Check whether you have some audio mixing tool running as a tray icon or something, if so make sure to uncheck all the features that supposedly improve the quality of the overall sound output of your system. In either case reducing the volume levels in the game options should be enough to fix the issue, even if it's caused by an external software amplifier as that should suffice to get the volume levels of the whole system down to healthy levels during gameplay.