I'm using Audio Technica M50x. When I change volume, I hear crackling on the left side. It's doesn't affect listening to anything but it gets me worried. I've only got it for 1.5 year and now. It also isn't constant. It occurs only when I'm changing volume. I tried with different cables but still the same issue. It's nothing wrong with my headphones, but something with the input doesn't seem right to me. Any thoughts and advises? Thanks!