How can I digitally merge two sides of stereo into mono sound? I'm deaf in one ear, which means I can't use earbuds as I can only hear one side. I've tried an adaptor that mixes both analogue signals electrically, but the sound quality is noticibly reduced.

What I'd really like for the software inside the phone to digitally mix both sides before it becomes an analogue signal. Is there a setting or a downloadable add-on to do this?

(I use the built-in music player and 'Google Listen' podcast player on a Samsung Galaxy S2.)
I would think that one of the one-ear bluetooth headsets would do this automatically.