I was a bit surprised when I got my new 770amp and then adjusted my calibration. All my speakers had to be adjusted UPWARDS from my receiver inputs instead of what I predicted downwards.

My thoughts was that since I more than doubled the power to my system with the amp, that my calibration adjustments would have less power needed to my speakers. However it was just the opposite.

Is this common? Does anyone know why my thinking was incorrect on my calibration?

That does seem a bit unusual to me, but not particularly worrying. When I added an amp to my last receiver (the Model 1050), I had to make very little change to the calibration settings even though the available power nearly tripled (from 65W to 165W). In your case, it may have something to do with the way the Onkyo's pre-amp outputs work as compared to the internal connection to the receiver's amps.