Yeah I didn't have to be convinced about the legitimacy of the thx 365 speakers but I was wondering if the paradigm in walls were legit as well or if the monoprice was even better?
I doubt those paradigm will have the power and spl. of the Monoprice. However the Paradigms have back boxes. If you get the Monoprice I would build back boxes. This will improve the speakers and above all avoid you blasting all that power into the wall space.
In wall installations are tricky. I did my first one fours years ago. I did use back boxes and designed them as sealed. The sub is a TL.
The biggest problem I had was to deal with the wall reflections, which caused havoc. I found I needed to crossover at 150 Hz, which I could do as the sub was right below the center and between the left and right. The driver had reserve of top end extension. It has now settled into a really good system.
Unfortunately you bought those Paradigm subs before you posted here. I actually doubt those subs will have enough top extension to even cross properly to the other speakers. The F3 of those paradigm speakers is 94 Hz.
When I look at commercial in wall designs, I don't think they are very intelligently thought out generally. I see cobbled together designs aplenty.
I do have one reservation about those Monoprice speakers, their impedance is 3 ohms in a good deal of the power band. So they will require potent and stable amplification. If you drive a receiver hard it could blow up. I note you have a pretty big space. What you are attempting is a far bigger technical challenge than you realize.
The dealer will just want to sell you what he has. They all do.
I am truly concerned you are going to spend a lot of money and be very disappointed with the end result.
It would be much easier if you were not wedded to this in wall design, especially as a novice. I can tell you to get a high quality in wall system is a significant mountain to climb.
It was a pity you had done the deal on those subs. I have serious reservations about the design of those subs.