During the focused R&D period of perfecting the PRO-EXL line, DS18 identified the opportunity to spawn off another line since there was a division amongst competition audiophiles and concert/"voceteo" audiophiles. Therefore, DS18 created the PRO audio line, which features a wide variety of midranges the produce concert-like sounds that will knock the wind out of you. A mid-range driver is called upon to handle the most significant part of the audible sound spectrum, the region where the most fundamentals emitted by musical instruments and, most importantly, the human voice, lie. This region contains sounds which are the most familiar to the human ear, and where discrepancies from faithful reproduction are most easily observed. It is therefore paramount that a mid-range driver of good quality be capable of low-distortion reproduction.