Audio "muffled" on Media PC

I have a Windows 10 PC running Plex Media Server and Plex HTPC.
This PC is connected via HDMI, to a Samsung TV.
I turned off the TV with the remote, and turned it back on again a couple of hours later. PC was running ther whole time.
And now, the sound is muffled, like someone is holding a pillow over the speakers (noone is, I checked!). The sound is equally muffled on media played through Plex, media played through MPC, and on Youtube.

I am pretty sure this is a windows 10 problem. I’ve encountered the same issue before with other hardware.
But I can’t for the life of me figure this one out.

What I have tried:

  • I’ve tried turning it off, and the non again.
  • Physically unplugging the HDMI, and plugging it back in.
  • checked that the correct audio output is used, tried switching and switching back as well.
  • checked TV settings and audio modes, tried all four and they all sound the same.
  • tried playback through different media as described above.
  • tried updating drivers.
  • tried uninstalling audio devices, and reinstalling.
  • Probably something else too, but can’t remember now.

Any ideas?

Solution found!

Shutting the TV down, and unplugging the power cable, then replugging and starting back up solved the issue.