I'm a little confused on which setting I should use with my B&K model 2230 SPL Meter, Preamp & Mic.. I have 4 choices, keep in mind these weighting filters are actually processed within the SPL meter and output through the sound card and REW. Maybe all SLP Meters do this, just thought I would mention it FYI. OK, I have "A" "C" "L with 20Hz & 20KHz rolloff, and "L". Should I use "C"? If so should I tick or untick the "C Weighted SPL Meter"" box under "Type" in REW "Mic/Meter" tab under "Settings"? In the help files I read that if I use a preamp & Mic I should uncheck the "C" box. Well I believe I have a preamp & Mic, so I'm confused on what to put my SPL Meter on and whether to check or uncheck the "C" setting.