There was of course never any such moniker as “ESL-57,” except in retrospect, to distinguish it from its distinguished successor the ESL-63. Designed by the legendary Peter Walker and actually introduced in 1956, it was called simply the Quad ESL, but soon became known as “Walker’s little wonder.” Little wonder: For top-to-bottom clarity, coherence, transparency, resolution, openness, naturalness, and a disappearing act that still inspires awe, the ESL established and remains to this day (even though production ceased over a quarter century ago) a reference standard among countless designers and reviewers (including the undersigned) across the globe. Despite undeniable limitations—inability to play very loud, lack of deep bass, quite directional highs—it tops virtually every list of the best, the greatest, the most significant—supply your own category—audio products ever made. Why? Because at the dawn of the stereo era this “little” wonder demonstrated what was possible in most of the essential areas of speaker performance so validly that from a certain point of view the subsequent history of speaker design has been catch-up.