RHA's Wireless Flight Adapter makes any headphone jack wireless - The Verge
Bose Single 1/8" Stereo Female to Single/Dual 1/8" Mono 40399
Gold Plated Airplane Flight Headphone Adapters (Pack of 2) | Allows you to use your Earphones with all In-Flight Media Systems | This Airline Plane Headset Converter Enables Great Sound on all Planes