Hi, I am building a 5.1.2 Dolby atmos system with a single SPS as CENTER placed horizontally and MPX speakers doing duty for LEFT ,RIGHT, SURROUNDS, and Heights. The Front and Heights will be installed in a stud wall and ceiling having more than 1.5 Cubic feet of air behind them .However I have a double-brick wall on both sides , and have to install the sides surrounds by making 4" deep holes in the brick wall. Is it advisable to install MPX directly in brick wall after lining the holes by glass wool . If it's not possible please suggest some other way .

Since the MPX needs a cavity of at least some volume to produce any bass, you might be better off using our SuperSat 50 on-walls for that application.

Thanks for prompt reply. I would be obliged if you can clear some doubts about the installation.
1) I am already committed to MPX , I can make a enclosure for them. What is the minimum airvolume for single MPX for surrounds.
2) I know from having read the blog , that the ideal material for enclosure is 3 3/4" ( 18mm) MDF. Is that correct. Any other thickness MDF can be used as 18 mm is difficult to procure.
3) does the MDF enclosure have to be airtight and sealed. It will have a lining of glass wool.
4) can wall- paper be used on the paintable grill and holes made in the wall paper.
Thanks and regards

1) 1.5 cu.ft. for good results.
2) 3/4" MDF is preferred, yes
3) Does not need to be airtight but you should avoid holes that can act as ports.
4) I suppose - lots of holes to punch...