Hi all: I've been using my GK MB500 and an Avatar SB112 for upright gigs and enormously enjoying the lightness of the head. I was wondering if anyone knows with some certainty what setting of the 4 EQ knobs on the MB500 would take the amp closest to flat frequency response? I've been keeping the contour and boost off, and taking 12 noon to be flat based on the cut/boost description in the manual. However, on many amps, flat is not at noon. Anyone know if the flat points for those EQ circuits is at noon?