Audio trouble - Zoom H6 USB to headphones connected to Realtek hardware in Windows PC

Thanks very much basroil. I accessed these same menus through the Control Panel already; no luck. I tried just now the way you suggested after putting the H6 to "audio interface" mode, "stereo mix". for "PC/Mac". As soon as I plug in the USB cable to my PC, I see the "ZOOM H and F Series Audio" item appear on the device list in the "Recording" tab of the "Sound" panel - which looks right to me. On the "Playback" tab in the same "Sound" panel, I see my "Realtek HD Audio 2nd Output" set as default device, my headphones are plugged into that port, and they definitely work with all other input sources. I'd insert snip of these panels, but it looks like only text can be entered here. Do you have any other ideas? I have Audacity installed, by the way, and no matter what I do, I can't get it to receive any input, even though it too recognizes a "ZOOM Recording Mixer" as the audio source. No signal present - not even a flicker! By the way, I have also confirmed that I can copy a file from the H6 through a line input of the Realtek, but my objective is to stream it via USB. If I have to copy then transfer, so be it, but that's not at all convenient! Thanks again - hoping there is a clue here somewhere as to why USB audio input isn't working for me.

Thanks again, basroil. Yes - I had tried setting Properties in the Recording tab already. Here is how I set them:
General tab: Manufacturer shown as ZOOM, Device Status indicates "This device is working properly".
Listen tab: "Listen to this device" box is checked, PLayback device set as "Default Playback Device", which are my headphones, and I've confirmed they work. Radio button indicates "Continue running when on battery power".
Levels tab: Set to maximum, 100, speaker icon shows enabled, and balance shows 100 for both channels.
Advanced tab: 2ch, 16 bit, 44100 Hz (same settings as my H6). The Exclusive mode ("Allow applications to take exclusive control of this device) is NOT checked, but I think I tried it both ways to no avail.

Thanks again for your help - any other ideas? Is there any way to determine whether I have audio data at the input of the PC? Cheers - Trevor