it is working now with my AC-AC adapter 
YAY! The voltage is more accurate with this AC-AC adapter than it was with the ZMPT101B, with the ZMPT101B I was seeing +/- 1 volt. With the AC-AC adapter I am seeing +/- 0.1 volt.
I still plan to modify the ZMPT101B removing the op.amps to see what it does for it, however I now have a working system, about to do the rest of the calibration and make sure current and powerfactor all look right.
Yes, I found it very interesting indeed!
Now that I am working with the AC-AC adapter and trying to dial in the calibration with it, I have made a new thread (Arduino Due Calibrating Voltage sense +/- 0.1 at first, now +/- 0.3 what does it mean?) instead of continuing to post to this one.
I will come back here later when I play with the ZMPT101B some more.