Need to push plug into the adapter very hard on first use. I use it to listen to both ipod tracks on one half of a pair of earbuds whilst lying in bed (uppermost ear) . I cut off the other silent earbud. Essential for 1970 wide spaced stereo like Hendrix, and for insomniacs!
The jack is a robust and well made item, I was struck by its size and weight. Unfortunately as a jack on my mp3 player with lightweight headphones it is a bit too weighty and is somewhat clumsy for this use. Probably better suited for larger headphones or in a static setting.