Dean, you probably didn't mean it this way, but I assume that when you copied the flat curve to the manual EQ(which actually can't be done)that you didn't listen that way, i.e., using the manual EQ setting rather than Audyssey.
My comments on Audyssey’s performance are based on having the EQ set to and tested with the following EQ settings after running the “Auto Setup/EQ“ on the Denon…“Audyssey,†“Flat,†and “Manual†(manual when using the values copied over from the “Flat†curve).
As for copying the “flat†curve there is a menu option that asks if you wish to copy the “Flat†curve to the Manual EQ function which appears to sample the “Flat†curve at the 63, 125, 250, 500Hz...etc. bands and set the EQ for each speaker accordingly. The menu also gives you the option not to copy over the “Flat†curve which then displays the “Manual†EQ with all bands starting at 0dB. Either way you can then adjust each speaker’s settings manually at the available bands.
From my reading it seems that the “Flat†curve and the “Audyssey†curve are essentially the same except that the “Audyssey†curve rolls off the high end some and the “Flat†curve does not, meaning the settings for the lower bands are the same for both curves. Listening to the “Audyssey†curve, “Flat†curve and copied “Manual†settings all yielded the same hollow tinny sounding male voices.
So no the curve itself is not copied but the values at those frequencies bands sure appear to be, thus giving an approximation of the curve it‘s calculating and applying at the low end.
I did experiment with the manual EQ after copying the “Flat†curve over by taking the copied values from the “Flat†curve and tweaking them. Mostly I just bumped the 63, 125, 250 bands back up toward 0. The result was that the higher toward 0 I boosted these bands the less hollow and tinny the male voices sounded.
