Originally Posted by lin821

What Weez_1000 said.

It doesn't matter where you buy your headphones. It only matters which headphones you buy. Some come with the adapters, some don't. Depending on the airline seats, sometimes you don't even need the adapters (I think).

If you have a specific headphone in mind and are flying a particular airline cabin, spell out the details so folks can tell you a more definite answer.