Calibrating the mp2 and your recorder
1. Send a signal to the mp2. Use something broad-spectrum at a constant volume/output like white noise. You can do this with mics up to your speakers or line in - doesn't really matter.
2. Crank the mp2 up until you're hitting red (I think that's +16, but I don't have the unit in front of me.
3. Monitor levels on your recorder. If you recording device has a gain stage for line in, turn it down until you're hitting -2 on the recorder (or just below clipping - depends on how good your meters are).
4. Tape down the recorder gain knob - you don't want to change this!
5. Now turn up the mp2 all the way - you will obviously be clipping your recorder now. Use only the limiter to adjust the output of the mp2 so that the recorder returns to hitting -2.
Once set, if you don't change the gain on your recorder, it will be impossible to clip it, no matter what you're feeding it with the mp2. This is good for stealthing because once you set your levels, you know that if it gets a little louder, you don't have to fiddle with the knobs to avoid clipping.