It's almost as if Apple didn't learn anything from the recessed headphone jack fiasco with iPhone. The MacBook Air, my friends, also has a recessed headphone jack.
While it's not nearly as bad as the headphone jack on the iPhone, the MBA's headphone jack is similarly recessed preventing a good number of headphones from fitting. (iPhone's recessed jack has never been officially explained but theories exist.)
I noticed this last week attempting to record the first PowerPage podcast on the MBA when my favorite DJ headphones (Technics RP-DH1200's) wouldn't fit into the teensy jack. Granted the Technics have a largish, 45 degree angled connector on the male end of the plug – but they fit fine into my MacBook Pro!
Some third-party audio products, such as headphones, may not plug into the MacBook Air headphone jack because part of the connector does not fit within the port hatch. In some instances, it may appear to fit, but the audio quality is intermittent or poor when used with MacBook Air.
Use a third-party headphone adapter to extend the audio connection outside of the port hatch. This enables a complete connector seating and electrical connection. Adapters are available at the Apple Store.
I realize that the jack's recessed so that the port hatch on the MBA can close and that it's a tradeoff for size, but it still bugs the hell out of me. Not surprisingly, Apple's iPhone earbuds fit into the tiny port without a problem. Hmm...
Apple would most likely label this as a "third party opportunity" (for the likes of Belkin, Griffin, RadTech, Shure et. al). I call it annoying.