So I bought the dayton emm6 mic for measurement, connected to M-Audio FireWire solo connected via firewire to my win7 htpc running REW and minidsp and all was well when I got the connections working but after calibrating the sound card it seems I have a 20db notch at 50hz which I don't believe is really there. I think I would be able to hear and see that kind of hole during a sweep. Is it possible it's the mic? I know people were sending back their omnimic sets and this uses the same mic ( I believe). It has a 4 digit numerical calibration code. So after hours of fiddling, I balanced the 3 sub amp levels in minidsp and let the receiver do its calibration like Audessy. Harman calls it EZ setEQ and it works pretty good.