I'm using the UMM-6 with calibration file, but I don't get the message that calibration is not needed, and when I do a measurement the window on the left says mic/meter: no calibration file. In addition when I try to calibrate the sound card to get inputs to -40 to -50 range (with the output generating -12db signal), I can't get there without the speaker volume getting uncomfortably loud. Then if I try to do a measurement it tells me the at the levels are too low (like -56db). I'm using an apple laptop with USB output (plays music just fine) and the mic on a usb input. I am guessing the input is too low, but I thought that was set with the calibration file from Dayton. Not sure what I'm doing wrong.