The 2011 Macs are preUEFI so they do not expose all devices at the EFI level, but they do in the CSM-BIOS layer that Bootcamp uses. If you want your Audio devices to show up, you will need to use CSM-BIOS (and hence Bootcamp). If you already have 3 partitions, they are not supported under the CSM-BIOS Bootcamp installation.
Bought Creative Labs Omni Surround 5.1 external USB sound card. Windows sound works for now. Just need to find a legit Windows 8.1 Key on sale. Almost done with getting Bootcamp loaded with all my games!