There is a critical bug in the Waves MaxxAudio Pro Application installation script. The user sees the message when attempting to install the app: 

Install Waves MaxxAudio Application failed.
Potential reason: The system already exist a higher version.
For other case, please contact Dell service for more detail solution.

As a result, the app is not installed and users can't use audio devices (headphones, headsets, mic) attached to jack input. There is the workaround to install the application in a non-standard way:

1) extract Waves-MaxxAudio-Pro-Application_MT722_WIN64_4.0.47.0_A06 (e.g. using 7-zip)
2) run 78bd34d730d945429d46cdc1ca9af246.appxbundle in order to install the app

Afterwards, the Waves MaxAudio will show a popup to choose type of input audio device whenever it is plugged into jack.