So I’ve had these cans for a while now. Picked them up for about £80 in an Amazon sale in July, and for the price I was very happy with the noise cancelling, isolation and SQ, though they’re not the most comfortable imo, and buttons are a bit stupid. I hadn’t used them for a couple of weeks. Dug them out of the car, put them on, and there’s this weird hissing/rushing noise in the left ear. This is ONLY when noise cancelling is on, when I turn it off, it goes away. They’re definitely still cancelling noise, though not as well as before. And the noise is too distracting to use them in NC mode, it’s not quiet, is audible during playback, and the balance is off too. When I turn NC off, it goes, but bass response is suddenly noticeably weaker. Any ideas? And without the box and accessories (I ususally keep them!) have I got any chance to return them to Amazon?