Have you set the hdmi audio device to be used as the default device?
View attachment 192073
In the Windows 'Playback Devices' control panel, if you select HDMI output and hit 'Configure' then run the speaker test, do you hear anything?
If you click on the LAV Audio system tray icon (when MP is playing), I *think* LAV can show you a live sound 'levels' display somewhere, which should enable you check if sound is getting that far i.e. LAV is decoding it (assuming bitstreaming is disabled).