For my second run, (with the left-front and right-surround speakers plugged) my graphs are attached to this post. I did this one late at night, and there was much less background noise.
All the levels were the same as the first run, except the FL, which increased from +1 to +2, probably because of the port plug.
On the left-front, the deviations are smaller, but now range up to 150Hz. The right front got worse, even though I didn't touch that one, with deviations below 70Hz.
The center picked up some extra bumps from 80 to 200 Hz, and even the Subwoofer is not quite as smooth as it was.
The right-surround smoothed out, but picked up a new bump below 40Hz. The left-surround, which I did not touch, is not tracking as well as it did the first time, especially below 30Hz.
So which are the important deviations, and which ones can be ignored? Am I obsessing over nothing?
Descartes' corollary: I don't think very much, therefore I may not be.