Hey man,
I have been solving this issue for more than a year and I believe that we are dealing with broken drivers from CREATIVE side.
I also have X4 sound card and running hi-spec PC, disabled integrated soundcard drivers and my issue is that I am loosing DDL or DTS decoding and I believe that those cracking sounds are only when we are setting our cards to work through SPDIF/OPTICAL inputs.
My case is that I have installed latest drivers and when You go into Creative app and set your speakers to 5.1 Dolby Digital Live and when You press test it does not recognize 5.1 CH, basically it runs test inside to each channel and sound is like you have 2.1
Other weird thing is that when You go into Win Control panel -> Sound Settings and into SPDIF props - There we have DD & DTS when You press test - IT clearly activates every single channel as it supposed to be but not in Creative app TEST on 5.1 DDL. It gets even weirder as I have uninstalled Realtek audio driver and Creative as well and my X4 lights are off now but still when You go through Win control panel Sound properties You can test DD & DTS and every single channel works as it should. I have no explanations for this matter as I have teared apart most of the forums and YT videos.
As I am using Logitech Z906 5.1 speakers many ppl complained that these speakers are giving out cracking/popping sounds but that is not the case in this matter & issue is with Digital decoding in my opinion.
For now latest what I have found is this thread on Redit:
I will try to work around this and see if my DD and DTS will be back without any cracks.
There is always a way.
More deeper You go,
More knowledge You know.