Although in other threads David has said he does not have the same experience as I, but anytime I have run w/ a battery box in front of my AD-20, the levels are hot as hell on the NJB3... the only time I could record like that was with quiet music (and it turned out quite nicely). If you have high SPL's, you'll need an attenuator.
And yes- I had mics->bb->AD-20->NJB3, and w/ no attenuator, it was peaking all over the place on the NJB3, even when I had the knobs on the AD-20 turned all the way down.
'tis my experience.