Auto levels for event PA
 

I use two Zoom H2s to record the PA systems at wedding receptions. It's tricky to get the right level without knowing how loud the DJ will crank it. I remember how well the auto audio level worked on my Sony FX1 and wonder if there is a similar system I could use with my Zoom or even one of my HMC150s. Do they make small external components that will do this?