I knit a 3 to 2 stitch I-cord around my headphones cord. I used two size 3US DPNs and Lion Brand Incredible in Arcadia. Now they are much less likely to get tangled or lost, which is awesome because all of my headphones tend to disappear or break. Having a little sweater on them might actually help protect them a little bit too, since most of the way they tend to break in my life is with them being wrapped up too tight and bending in the wrong spots so the wires disconnect.
If you want to do this to your headphones and you don’t know how, feel free to ask. It’s super easy, will keep you busy for an hour or two, and the end result is pretty nice.