By default, the number of output HDMI audio channels used by Windows is controlled by the settings in the "Playback devices" tab of the Sound menu. Some player programs override it, but most don't.
1. right-mouse-button click on the speaker icon at the right end of the taskbar
2. Select "Playback devices"
1. Start menu --> Control Panel --> Small Icons --> Sound menu
2. Select the "Playback" tab (the default)
3. select the HDMI device (usually at the bottom of the list of devices)
4. select the Configure button
5. Select the desired number of HDMI channels. (Stereo is usually selected by default)
6. select the options to test the audio outputs
7. Click OK until exited from the menu.
Marantz SR7009/7.1.4/FH+TM/DefTech PM1000/LCR+TM amped