Just a quick solution I have found for my ground loop hum, which was coming through my sub. After spending too much time and money trying to figure it out, including replacing my sub amp and the Wiim I finally discovered that the hum disappeared, like some of you have discovered, when I removed the HDMI cable.
I have now discovered this is resolved by removing the aerial cable to the TV. This is not a fault of the HDMI or Wiim, this is due to having two different earths between the aerial and the electrical of the tv and is a common issue I've now discovered across HDMI electronics and TVs.
So, in my case, I just needed a cheap isolator for the aerial. Wish I knew 3 months ago.
I hope this helps someone.
Matt
