I know you’ve tried uninstalling, but have you already tried manually removing the driver?
First, here are the instructions on how to check if the FxSound driver was installed correctly:
To confirm if FxSound driver is installed correctly, go to the directory %PROGRAMFILES%\FxSound LLC\FxSound\Apps and run this command from command prompt,
DfxSetupDrv.exe check
The output should be FxSound Audio Enhancer
Also if the driver is installed, it will show up device manager as follows,
And here are the instructions on how to manually delete the FxSound driver:
If the driver gets installed but the device instance is not created properly in device manager, we can try removing the device manually, by uninstalling the device with “Delete the driver software for this device” option checked.
If the driver installation again fails and shows sign in the device name in device manager, share us the installation log file %WINDIR%\inf\setupapi.dev.log
Also, as mentioned above:
There are two reasons that I can think of for audio not playing through FxSound.
If there is any other audio enhancement application running on the PC and if the audio playback device is setup for exclusive mode, then the other application can take control of audio playback and FxSound will not be able output audio to the device.
I have attached a sample screenshot of the setting in Control Panel → Sounds.
Also, FxSound should setup as default device and default communication device in Control Panel → Sounds → Playback. If any application chooses the default communication device for output then the audio will not go through FxSound.