No issues here with my X-Fi Xtreme Music.
So i'm "shooting in the dark" so to speak since i havent had the issue.

Be sure you have latest creative drivers.
Try setting speakers to 2.1 in the creative console and under windows control panel
And be sure to have all the options in the creative console set to their defaults.
And just for kicks, i'd try disabling DOF for cutscenes or even try the lowest graphic settings just to test and see if that helps at all.

I have the same sound "crackling" issue during the animated cutscenes, but it doesnt happen all the time.

I have an xfi XtremeMusic, and i constantly change between 5.1 and 2.0 depending on whether i'm wearing headphones or not (playing at night vs during the day).

When i go home i'll try comparing both modes in a cutscene and check if only one causes the crackling.

I had this problem but was able to fix it. I have an Asus motherboard and had the EPU-6 Engine running. Apparently that program either under- or overclocks the CPU ever so slightly in every power mode OTHER THAN "High performance". High performance mode leaves the CPU at stock speeds. And keeping it on High performance fixed my crackling cutscene audio.

If you don't have EPU-6 or an Asus mobo, you might want to look into any other power saving -programs you have running that tamper with your CPU clocks.