I had to sweep the electronics with REQ to find my problems with Audyssey....
It went like so:
Response curve of receiver with Audyssey off:
Note the decreasing response below 10Hz, typical of most audio equipment.
Now engage Audyssey:
Note how it places cuts where needed. Also note how it does not place any cuts below 20Hz, or above 250Hz. Of significant note, the overall level has been increased, to make the apparent overall volume equal between Audyssey on and off.
Both traces together:
You can see that below 20Hz, there is a SIGNIFICANT 'boost' happening because of the level change, which was causing my sub to distort. Hence the purchase of the reckhorn.
Now, to see that it is just a level issue, I move the Audyssey on trace down by 10dB:
10dB is the same as 10x the power. SVS uses an amp similar to mine, and some SVS owners were also complaining that Audyssey was 'boosting' the extreme low end too much. What I did with my amp/reckhorn combo is essentially fill in the dip between 20 and 15Hz with my amp's freq response, and used the Reckhorn to eliminate the sub-15Hz 'boosting' Audyssey was implementing.
As for Dynamic EQ, I really like it. It reads volume frame by frame and adjusts eq according to equal loudness curves. Louder passages get less eq, softer passages get more, and the level of eq varies not only by source content but by master volume setting. At 0dBMV, no eq is added to anything. Many terabytes of data implementing equal loudness contours as well as pro mixers' input was used to make the algorithm. Dynamic EQ alters the levels of the surrounds, boosting them a little as the volume is decreased. It is a prominent effect. Switching between Dynamic EQ on and off listening at -15dB, with DynEQ off, everything collapses to the front 3 channels. My one complaint is that at very low volume levels (-20dB or lower), there is too much bass. I think the algorithm is great for listening down to -15dB, but lower than that and it sounds strange, too much low end.
I have measured the boost, and at -10dBMV, with a -3.0dBFS sinewave sweep, it applies a maximum of 3dB of low end boost, more boost as you delve lower in frequency.
Why I HATE dialnorm is that it changes the Dynamic EQ algorithm. For movies that have the -4dB offset, to get equal level, I turn up to -6dBMV. That means Dynamic EQ is applying less changes, less low freq boost. The difference became apparent with the two versions of TF2. I bought the standard version, not knowing the big screen version existed. When I got the big screen version, it seemed to lack authority, due to the dialnorm. When I turned it up to -6dBMV to match, Dynamic EQ did not apply as much changes, and while it was close to the same level, the low end had slightly less punch and depth, because DynEQ was applying less change...it is noticeable....less kick, less shake, less rumble. And we are only talking about a few dBs here...it seems tactility of bass freqs is highly dependent on level.
Dialnorm now explains why movies like the Hulk are the loudest I own, no dialnorm offset on that one or Master and Commander...