I finally got a2dp working. I had forgotten what stereo sounded like. I reset everything and tried again. I think my problem was I kept testing audio in kagu, and maybe a setting was wrong and it wasn't playing with mplayer. I tested audio in kmplayer, and it worked and now I've configured canola to play in stereo. So the fact that I had never heard stereo in the headphones before and my pc dongle wouldn't work and that kagu wasn't playing stereo made me wonder if the headphones were defective.