This took way too long to find. If you have the Plantronics GameCom 780 USB headset like I do and you reinstall your OS, you may have trouble finding the driver download for the Dolby surround. They work just fine in Windows 8 via plug and play, but the Dolby surround doesn’t work. Here is the link to download the drivers:
For some reason, Plantronics has hidden that download extremely well.
Then, in Windows 8, after it has extracted itself (which it does into Program Files (x86) without any warning), you have to right-click the Setup.exe, click the Compatibility tab, and tell it to run in Windows 7 compatibility mode and as administrator.
The setup will take 30-60 seconds. When it’s done, everything will work (even without rebooting). The tray icon should show up and clicking the button on your headset will switch on Dolby Surround mode.