I've not heard of HDMI noise before, and it seems impossible that it is being transmitted via the HDMI cable because it is a digital signal, but there are references to similar online. e.g.
https://www.techhive.com/article/3063590/home-audio/how-to-get-rid-of-hum-and-eliminate-other-noises-from-your-audio-and-video-systems.html#toc-5
http://www.epanorama.net/documents/groundloop/
Try if possible plugging the A11 into a different wall power socket.