Answer:
(Pre-requisite, the PC/Laptop must be connected using a wired ethernet cable to the same network as the the Q Active system is installed (Q Active Hub can be wired or wireless.))
Yes, both the Windows and Mac versions of the Qobuz desktop app allow playback to the Q Active system, simply click on the loudspeaker icon bottom right of screen, and this will open up a list. The list will show 'INTERNAL' audio sources built-in to the PC or Laptop, and 'EXTERNAL' audio sources, you should see 'Chromecast' in this 'EXTERNAL' list, click on the '+' sign next to 'Chromecast' and will reveal a list of Chromecast enabled devices on the same network that the PC/Laptop is attached to. In the list of discovered Chromecast devices you'll see the Q Active loudspeakers listed with the name that you assigned them at setup in Google Home, now click on that name, and play should start on the Q Active system.
Clicking on the volume slider for the first time may cause a jump in either direction of the volume on the Q Active's, but you'll then be able to alter the volume from within the app, please note that any adjustment externally via either the remote control or loudspeaker control panel will effect the volume, but this will not be reflected in the volume level shown in the app, and again, if you click on the app volume you may find it will jump.
All transport functions are available within the desktop app.