The 83db/watt sensitivity rating is a realistic average of the response curve.  Some commercial loudspeakers are very optimistic with their sensitivity ratings.  They must rate their speakers based on the peaks in the response curve.  I previously owned a pair of "86db/watt" well respected British loudspeakers.  Given the same turn of the volume knob they sounded quieter than the 1801.  Stereophile magazine reviewed and measured a "86db/watt" well respected two-way floor-stander that fell short of the sensitivity rating.  Stereophile wrote that the 86db rated speaker actually measured 84.5db/watt.  Another review found a well respected speaker rated at 87db/watt actually measured 83db/watt.  This is quite common.  I write this because the educated listener may want to know if my sensitivity rating is based on liberal marketing or a realistic average.  The latter is true.