This is my first trial, no smoothing, the blue trace is with the minidsp filters generated from the Audyssey curve. I try using it with Audyssey off but it seemed hopeless because the "off" curve is just way too ugly to the mini to do anything.
View attachment 22270
From what I can see so far, the minidsp 2XHD can definitely make the frequency response smoother but in terms +/- it cannot do better than Audyssey by more than 1 dB, though I have not try re-running Audyssey.