After buying an Ultimea A60 7.1 (more like 5.1.2 but who cares) Dolby Atmos surround sound kit, i wanted to use the manufacturer provided wall mounts but all mounts will place the speakers at a 90° angle compared to the wall,a nd the interfaces are loose, so it will add a lot of unnecessary side effects.
I looked up proper speaker placement and found some simple calculations to make sure your "soundstage" is optimal.

The front speakers need to be placed apart the same distance as the viewer is away from the video and sound source. I am about 2.5 meters away from the screen so the speakers are spaced 2.5 meters apart under 30°  on each side to create a equilateral triangle.

The rears are angled at 15° from the rear wall, and under a 22.5° pitch for a placement of about 3-3.3 meters apart, to ensure a wide soundstage.

The soundbar is placed on 2 kickers that angle the sound output towards the viewers ears directly, i placed them under the rubber feet of the soundbar to ensure isolation of the bar and to eliminate any rattling.

Keep in mind, the mounting screws are fitting very SNUG into the mounts, this is a deliberate choice, i use CF-PA for these mounts that add additional damping. Also, THIS KIT IS DESIGNED FOR MY SETUP BASED ON THE DISTANCE BETWEEN ME AND MY TV, if you want a custom made set, let me know and we can work something out.