iMac 21.5 late-2015 model boot camp driver support

Just purchased 2 - 2015 late model iMac's for boot camp purposes. The installation of this changed again... now, supposedly, Windows drivers are installed directly from the Mac OS partition. The version that installed was bootcamp 6.0.0 (love those initial releases...), but most of the device drivers in Windows (8.1) were not updated.

Found a link to the 6.0.0 software and manually unzipped the file so we could actually see all the drivers. We were able to assign drivers to the devices and cleared all of these driver issues.

But... what remains is problems with the sound. Was finally able, by choosing a variety of sound drivers, get the internal speakers to work in Windows. But... nothing plugged into the headset jack works (it does on the Mac OS side).

Currently we are using Intel built-in device drivers, but cannot find any mention of what the actual sound hardware is on this iMac (used to be Cirrus). We have also called Apple support and found a manager to discuss this week, but it has been 10 days. Would like this to work properly and know that we have the correct drivers installed for the hardware that is used on this iMac.