u/Acrobatic-Barber-637

In my home theatre the in-wall Centre speaker is cut through my 5” brick wall and fixed with the plywood box all around. As the plywood is visible on the backside, as the cutout is gone through and through into the wall, I am planning to have a 3mm MS iron plate on the backside to cover this. Will this affect the performance of my centre speaker’s magnets? Will it degrade my speaker clarity in anyway? My centre speaker is shielded very well in an enclosure of its own, it is from Monitor Audio cp-iw460x.

And there is a 12 MM plywood between the speaker and the metal plate.