When I have the boom on left side, all is good. When I have the boom on the right side (right ear), I get intermittent static. So, basically when I sit in right seat, I have to have the boom on the left ear to use it without static. NC on.
I thought this was a normal (albeit disappointing) feature of my USA A20 (which I've had for several years); until I got to try another A20 in flight (7X/8X) last week and found out it wasn't a normal feature (unless the headset I was trying last week was the outlier).