NightKnight

I think I'm having the exact same issue, it was much worse on my Marshall headphone. I went to the store to test the Marshall headphone on the sample PX-S7000, it was the same. The staff let me tested a few other headphones, it sounded better so I thought it was just some incompatibility issue. ThenI got Sennheiser HD599 hoping the hissing sound would be gone, but it's still there just less noticeable. It's really troubling me because this is an expensive product. How did you resolve it?