hi, I just bought a focal clear used in really good condition but the problem that I noticed is when I play song with deep bass like Bad guy from Billie Ellish I can ear the left driver making a metallic sound. I went on audiosciencereview and saw that Amir spotted this issue and I played the song that Amir said that he could hear the crackling noise and I ear it too. Why I'm writing this is because sometime the left driver crack but other time I plug the headphone and listen to all the problematic song and absolutely NO crackeling noise. Why something it crackle and other time not ? Did there is an explanation ?