So occasionally I see guitarist do this
Click here for Video

it seems like its just a cloth tied around the headstock,
unless its being used as a capo?
Last edited by onethat at Aug 18, 2013,
It's to dampen the strings. You know how when you play you mute the strings that you're not playing with the fingers you're not using? (you should do this for a clean technique!) Yeah, well the sock is there to dampen the strings so he doesn't have to waste any effort muting strings to get a really clean take in what looks like a studio.
"Air created the greenness. And once you've got something, that leads to otherness." - Karl Pilkington.
Try it, but don't forget that using something to dampen the strings will not cover up a bad technique. I would recommend using this only when you are recordind.
Yeah only really do this when recording, it's not very practical for a live situation. It basically mutes the strings he's not playing, how you're suppose to when you play but sometimes in the studio you just need it that 110% cleaner.
Check out Guthrie Govan and Andy James, they both use this for crazy legato techniques. It really helps to mute the other strings.