Hmm.... I think the sound fades when my computer is set to a low volume. I turned up the volume to 44% and then used my headsets audio wheel to turn it down. I fixed it.
Update: Just saw how many people have seen this thread, so here are some other suggestions if this didn't fix you issue.
One thing that's helped numerous people (including other headsets I've owned) is to disable communication audio muting. Go to your playback devices (right click the speaker icon in the task tray), and select the communications tab. Set it to do nothing. Skype actually uses this feature, and has caused lots of issues for me in the past.
Loudness Equalization (also known as Volume Normalization), excellent setting that can be enabled on most Realtek chipset. Open up your playback devices, right click your device and go to properties. In the effects section you should see a setting for "Loudness Equalization", enable and apply it. This will attempt to make loud audio quieter and vise versa for quiet audio.
I had done a lot of research into DPC, which caused an audio crackle. LatencyMon is a great program to diagnose the issue. My problems always stemmed from network drivers and network cards. I ended up buying a wireless USB dongle which works great, and seemed to not cause any serious issues.
Clean install of your audio driver! Yep uninstall it then reinstall it. This really does work.