But the problem you will get is vibrations, as the sud wall and the void that's between the plaster board will act badly to the sound produced from the speakers.
Depending on how good your system is, you will hear a difference in sound quality, and for the worse I am sorry to say.
I know this as I had a P8 mounted on a stud wall and it sounded thinner and not as detailed compared to the rack before
Precisely my (and others?) problem. The only way around it is to cut away the plasterboard, plaster and paint the resulting exposed brick, and try to make it look acceptable.
Or cut out a piece of plasterboard, drill the wall behind, insert threaded bars, use a two part epoxy to secure the bars, then build the wall out with a piece of DPC, some plywood or other materials, finish off with a piece of fresh plasterboard, tape and fill the seam, plaster, fill and paint, then mount the wall rack onto the threaded bars and secure with nuts, mark off the access and cut off, then finally secure with either two nuts to lock or Nylocs. That means your wall rack will be fixed to a solid secure wall.
But the problem you will get is vibrations, as the stud wall and the void that's between the plaster board will act badly to the sound produced from the speakers.