Hi
I had serious issues with the sound drivers in Windows 8.1, to the extent that I restored back to Windows 8 and haven't tried to upgrade again.
I found later that if I update my sound drivers in Windows 8 to the latest ones, all of the problems come back again.
Only the default Windows 8 drivers seem to work correctly. Not the ones from Creative.
So if you can find a way to reinstall the old Windows 8 drivers in Windows 8.1 you may be able to fix the issues.
Mike