This is quite interesting . I assume its all about isolation of any em picked up during the journey over the house network. I run a few powerline adapters to get the signal around different switches and APs around the house and have always wondered about any potential issues. (Before anyone asks, it's a victoriana house literally built into the side of a hill, the oposite of being wifi friendly and the power is not the best). I use usb isolation and optical at the moment where I can but as I said an interesting idea if there is any issues in the network. Assume you try and have as clean power as you can on the media converters