Need stereo to mono eaphones

[Tom Servo]

OK, I'm having no luck trying to find either an adaptor for my earbuds, or just a single earbud to play both stereo channels in one ear. I can play music at work, but we can only have it in one ear, and I'm tired of hearing just half the mix. I've ordered two adaptors from ebay for my stereo earbuds that claimed it converted stereo to mono. Didn't' work. One just put one channel on both sides, the other got no sound at all. Then I ordered a single earbud, that was supposed to output both channels. Nope. Still getting one side. Any recommendations?

To be clear, I'm not using anything fancy to play my music, no smart phone. Just a cheap mp3 player, like an ipod. No mono setting in the player itself.