I know on my Realtek Card , under advanced device settings there is an option to seperate or tie line in/outs etc together but I have never wanted to sing / record so Have not played with it but...

I don't have a Via HD so I can't really look into it more sorry , I just saw it mentioned on Reddit here (and a few other places)

Windows 10 - VIA HD Audio driver fix : windows

Try the Windows 7 ? or 8? Driver for the VIA HD you were using, if there isn't a newer one available , the Auto installed one from Windows Update/ in Win10, may not be 100% compatible with your...