Try installing the driver for win 8, if no win 8 driver then try the win 7 driver. If it still doesn't work then right click the win 7 driver, click properties and then choose compatibility mode for windows 7.
Have you tried setting your default sound device using the way outlined in the screenshot below?
Try un-installing the driver win 8 installed but before doing so make sure you change your windows update settings to 'check for new updates but ask me whether to download and install them'. Then, download the Windows 7 driver and try the compatibility mode mentioned above.