I have 2 of the DDRC-22D.
One is in use with the 2.1 video rig and the other is sitting idle at the moment.
The installation in the video system was transformational, can’t watch/listen without it.
The other has rolled in and out of the main listening system for several years.
Speaker placement and room treatments produced better results.
In the end filters from Home Audio Fidelity proved to work best.
Very easy to install in a system and set up.
I still haven’t upgraded to the latest Dirac software thats available.
I will be letting the idle DDRC-22D go soon, but without a mic.