Stereo playback as we know it for more than half a century uses two loudspeakers placed in an equilateral triangle in front of the listening position. With the listener exacly sitting in the so called sweet spot, this setup can reproduce a frontal localization, e.g. of an ensemble on stage or the band in front of us. To a certain extent it is possible to perceive depth and distance in good recordings as long as we find ourselves in a pretty neutral playback environment regarding it's acoustics and stay exactly in the sweet spot area. Surround sound was the next...