Chosen Solution
I have this Mac as my daily driver, and I regularly use the headphone jack. About a month ago there was crackling in the headphone jack only, and it has progressively gotten worse. It is not a grounding issue, since I’ve tried grounding the computer several different ways. The crackling is not present on powered devices like speakers, but for devices that rely on power from the port, like earbuds and headphones, the crackling is very noticeable. This has led me to the conclusion that the headphone amp is defective. Is this a board level repair?
As long as you are sure it is not an issue with the devices you are plugging in, the issue will be with the headphone jack itself. Check inside to make sure there is no dust, since this will also cause crackling. Replacing the jack is not easy, the part cannot be bought new either and has to be desoldered from another board. Call around to see if anyone will be able to replace this, but this type of repair is usually turned away by most repair shops.
