I have a behringer measurement mic, so I'm wondering what the easiest/cheapest way is to get the SPL measurements. I'd rather not go out and buy a dedicated SPL meter just to take one calibration measurement and then collect dust!
Theoretically I could take the measurements in the room without calibrating the SPL level, no?
Okay, I get it now. :T No reason I can think of why it won't work. Even if it's accurate, but it shouldn't be a big deal. Just run the Set Levels routine as normal, and set it to 75 dB as usual. Be sure and run Check Levels before taking the measurement. If it shows too low, or clipping, just re-run the Set Levels routine and re-adjust for 73 dB, 77 dB or whatever.
[Edit - it looks like brucek beat me to the "Reply" button. ]