Have sound, but Realtek HD Audio Manager does (almost) nothing

I use Logitch Z-5500 speakers (two front, one center, two rear, boombox). The optical cable is connected to an ASUS P5K motherboard.

I have the Realtek HD Audio Manager (6.0.1.7535). At times when I click the tray icon, I see a full panel of options (e.g. Sound Effect, Equalizer, Volume, etc.). But none of the controls do anything at all.

At other times when I click that icon, I only see this message: "You are seeing a blank page because there is no audio devices plugged in the system. To activate GUI please plug an audio device into the system."

I generally use the PLII Music or Movie Effect. Stereo or Stereo 2 only provides sound from the two front speakers.

What is going on? I know I need a 5.1 source (e.g. DVD) for true 5.1 sound, but what is the best setup to use in other situations (e.g. MP3s, YouTube, etc)?

The first thing I would do is update the RealTek driver.

I do not see a more recent version at the RealTek website.

download it anyway. then go to device manager and uninstall the sound card. Reboot and then install the driver.

It may be a Win10 issue though.