Thank you for posting! I am sorry things are not working fully as expected while using your Plugable UD-6590Z docking station and I would be happy to help.
Thank you as well for the detail you provided that is much appreciated. Based on your description, I am not quite sure if the ‘Unknown USB Device’ you mention is related to the audio behavior. As a result, our next step is to get some additional information and in order to do so we need to provide a little background information.
When the UD-6950Z dock is connected to your system, you should see an audio output device within the Windows ‘Sound’ settings called ‘Plugable Audio’.
The ‘Plugable Audio’ device represents the audio output jack located on the front of the dock, where you mention that your audio headset is connected.
It is important that the ‘Plugable Audio’ device be selected as the default audio output device and that the volume is adjusted properly in order to hear audio via the headset connected to the dock.
There is a good guide to how to select the default audio output device and change the volume level here --> https://www.tenforums.com/tutorials/102323-change-default-audio-playback-device-windows-10-a.html#option2
If you use those instructions as a guide, are you able to make the ‘Plugable Audio’ device the default and make adjustments to the volume level?
If you are not able to do so via that method, may I ask you to please post a screenshot (http://www.take-a-screenshot.org/) of your ‘Sound’ settings application, similar to my attached example? That will help us to determine the next steps.
Apologies again for the frustration, and thank you for giving us the chance to help!