I agree and disagree. You are cooked if you try it.
But if you could somehow invert the signal going into one channel you could, in theory take the balanced output to your speakers. I guess this could be done by getting two D/A's and connecting a digital output to both, set one of them on "invert".
So if you inverted the right channel you could connect the LEFT + to the speaker and the LEFT - to the RIGHT + (GULP!) and the RIGHT - to the speaker. In theory you should get MORE than double the power because you are doubling the voltage, but you are gonna draw a ton of current and probably blow it up because of that. If not you would blow it up because if the channels are not EXACTLY matched with the same DC and everything you are gonna fry. Hmm..... I wouldn't try it myself.