3 months ago I wrapped my headphone cable in ERS Paper that was hanging from the cable with scotch tape, the ERS Paper was 5mm from the surface of the cable. It made it sound worse so I had to remove it.
Today I tried it again and used toilet paper rolls and a cotton thread to suspend the cable inside. Now the ERS Paper is separated 1+cm from the cable. I'm not hearing any weaknesses at all, it made it better in every way!