I created years ago my "golden plate" as protection and filters : shungite+copper...I used as many as 50 as part of my electrical embeddings control.. ...With headphone i used them around my amplifier and no more in the electrical grid of the house because i sold my house and speakers now... ...
😁
I got mine for an off the wall company, but I know that Amazon sells the materials as well as some specialized companies that deal wiht ONLY this type of product:
https://www.amazon.com/s?k=emf+blocking+cloth&crid=2CVEND4OXVPX4&sprefix=emf+blocking+cloth%2Caps%2C138&ref=nb_sb_ss_ts-doa-p_6_18