Russell's line array doesn't just have required equalization, it has a special proprietary equalization. My bet is that he knows exactly where the comb filtering distortion hits and in what frequencies that it does. He's using a digital equalizer that specifically targets those frequencies to boost or cut.By doing that, he's able to make the comb filtering distortion appear lessened. I caution you not to try to make his version of the line array unless you are also willing to do considerable measurement, and then use either a 30 slider per channel constant Q equalizer(Rane preferably: looking at about $170 used on ebay), or a digital equalizer( price above $400) to make the comb filtering sound as if its not there.
Marlboro