This solution worked great on my Linux Mint 18.3 guest until I upgraded Windows 10 64 Pro to the spring creator 1803 update. After that upgrade, I get an unspecified error message that is not resolved with the "Stereo Mix" enabled. I've gone to my motherboard vendor's site (ASUS) and downloaded and installed the latest Realtek audio updates, to no avail. Also deleted all audio drivers and reinstalled the latest Realtek drivers. The funny thing is that a Windows 10 guest audio works great !! Even without "Stereo Mix" enabled.
With the Linux guest, if I don't enable the "Stereo Mix" in the Windows 10 host, I get the usual "out of range" message from VM Ware Player. However, when enabling "Stereo Mix" instead of the problem going away, I get a message that states an "unspecified" error has occurred.
I hope this issues can be looked into and resolved so that I can get audio working again on my Linux guest.