Lightly jiggle the plug in the jack. Listen to see if the crackling sound seems to be exacerbated by movement.
I suspect it will be. Probably the most common problem that causes this kind of cracking sound is an intermittent headphone connection caused by a damaged connector. When someone yanks on the cord - by accident or by "lazy disconnect" - it can easily damage the connector or the cord.
Movement did seem to make it worse, although the problem seems to have resolved itself for the time being. Not sure how that's possible. The night I ran into this problem initially, it seemed the problem was coming more from the remote than the headphones as the crackled continued through two different sets of headphones.