I am one of the people testing the Beta programing of the new DEQX units. My Pre 8 is due to be shipped out next week, FINALLY. The first thing that happened was COVID and they lost the supplier of the main processor they were using. They wound up redesigning the units around another, even better processor. It also required revising the programming. All this took two years. Then, a problem developed that required redesigning one of the boards and finally two out of the first 100 units built developed the same intermittent problem. They wanted to make the diagnosis before letting the other 98 units go. They are all PRE 8s by the way. Most people will require only PRE 4s. It is the identical unit without the 4 way crossover. It won't be available for at least another 6 months. So, take your time and play with the dBx. I've been doing the digital thing for almost 30 years starting with a Tact Audio 2.2X and I am still learning.
Your subs are passives! Did you build them? I have the same situation as you, an open floor plan and passive subs in a large room. Two 15's will do a lot of damage and is enough for a point source system.