If you tested under Windows right now, you do not have to test with different speakers. Changing speakers or using a headphone was just to make sure that there is not any quirk in the computer - speaker connection, but if you just checked under Windows than it should be fine. The Jack to be used under OS X might still be different.
vcn is a user, who posted besides other things, that he used a different inject value.
I do not use the Z170-A anymore so I can't check whether it may be related to the Multibeast version. Can't even check what jack, output device selection I used. On the Z170-K it was definitely internal and green. On the Z170i-Pro Gaming it is Lineout and black, but can't remember the Z170-A.
There are other methods of installing sound like voodooHDA, you might try one of those.
If sound didn't work, either the the device was not available, or it was something like Jack/device setting combination or the volume not set high enough somewhere in the output chain.
And without being able to see and feel the error, I'm not really able to help, sorry.