I think your system is acting atypical.
In most systems I’ve seen, Audyssey either doesn’t do anything harmful (meaning your Room is in pretty good acoustic shape) or it improves the FR.
There is absolutely no modulated background noise anomalies or any adverse effects done by Dynamic EQ in my system or other systems I’ve encountered.
It is not my system that is atypical it is me. I'm highly sensitive to audio aberration. Dynamic Eq is yet another in a long line of ghastly constructs of the musical pop culture.
The system is a dynamic compressor/expander that also alters the frequency envelope at the same time. Its interference to the original program is massive. Its object is to try and make the music of the pop culture more exciting and dynamic.
Now I hate all gated compressors and never used them in my recordings. I can hear them all in action. When I had to record program in the days were you had to use compression to fit the dynamics of the medium I used a conductors score and used sensitive manual gain riding.
This dynamic Eq is a far worse aberration as HF and bass are boosted in association with the musical dynamics. If you understand what is going on, it has to modulate the background, this is mitigated to a degree by the associated compressor. However on wide dynamic material where a good conductor can go to softest almost inaudible pianissimo to the loudest forte, the interference of this absurd construct is blindingly obvious. If you do a search you will find its only advocates in the pop confraternity.
To use it is actually a massive insult to the musicians and conductors. I certainly don't want the frequency envelope of their instruments changed at all, and especially not with a dynamic component. I certainly don't want the musicians and conductors dynamics altered in anyway.
Just read up on what this program really is and you will see what an awful hash of a program it is.
Anyone with any musical sensitivity would run a mile from it.
To top it off you really have to take pains to lock that program out hard. You have to do it input by input and make sure the lock is on when your finished. The creators have enough hubris to darn near force it on you.
That is a program only for musically insensitive philistines.