Did the background noise come up recently? If it's disrupting your listening experience, please send your unit to be checked at our service centre.
I've been wondering about this. I've sported my 180s for a year now, and it wasn't until yesterday that I picked up a rather whiney, somewhat high-pitched static background noise from the sound transmission. It's practically inaudible unless you are in a completely silent room or press the headphones tightly to your ears. Is it normal or are my phones broken? I tested it with two different sources, so it has to be in the headphones.
It's very reproducible:
1) Maximize volume on the headphones.
2) Listen to the beginning of this https://www.youtube.com/watch?v=L9h2o-rc4m4 (make sure to lower the Youtube volume to one third or less).
3) Press the headphones tightly to your ears. The left can alone should be enough.