To the people who say it suddenly works again:
Check your output device in Windows. Of course, you get interference-free sound when the output device in Windows sound control switches from Razer Surround to, for example, SONY TV *00 (Nvidia High Definition Audio) or Speakers (Realtek (R) Audio). As I said, I'm talking about the Windows settings, not the settings within the Razer software.
The problem still remains...