When I'm alone, I unplug my headset and let the sound output from the load speaker of my iMac, and when there are other people around, I plug in the headset in order to not bother people around me. I found myself keep plugging and unplugging my headset. What's worse is the headset jack of the iMac is on the back side of the screen.
Now I'm hoping that I could keep my headset plugged in all the time, and there would be a software switch to control the sound should be output from either load speaker or the headset. But I don't know if it is possible with a Mac. It seems to be possible with Windows, but I'm not sure. Anyone has any idea will be greatly appreciated.