Honestly, I don't know. Yes. But there are only certain places and ways one can do it. You can do it in the DAC, because it is done in the digital realm. You can do it at the speakers -- but not if they're electrostatics -- because there is no "ground" per se. You can do it in the preamp, but only if the preamp lets you, you don't want to do it yourself between, e.g., the preamp and the power amp, or between the source and the pre, because they might be sharing a ground, etc. It's just a matter of swapping the + and the -, I.E. changing the phase of the angle 180 degrees.