It's interesting to know you have questions to ask. B&O simply asked me to explain the problem which I did as fully as I thought necessary. They asked no questions or made any suggestions. They simply decided to ask me to return the Stage for a full refund. My local dealer sent round a guy to see if he could sort out the problem with the Stage they supplied and concluded that the ARC connections were the problem and that the TV was "at fault" But when two products are not compatible because they adopt slightly different ARC standards, who's at fault?
Here are my answers. Not in your order:
I used the cable supplied by B&O. My dealer tried his own high speed cable. Had no effect.
The sound output was set to ARC - the HDMI 2 socket on the TV.
Have no idea what the LG Sampling is. Not something mention by my dealer.
The only sources I used were my TV and Blu Ray player.
When we connected the Blu Ray player to the other HDMI socket on the stage, there was no problem. When I streamed music by blue tooth there was no problem. I didn't try the 3.5mm connection. I saw little point.
I use Sky Q with my TV. Everything coming through the SKY Q had the same sound interference - normal programmes, Netflix, Youtube etc.
Thanks for your interest.
Still waiting to hear from B&O. Perhaps they are on strike.