Planning to install diffusers but what's the point?

That is not exactly correct.  Most panels absorb sound, converting it into tiny amounts of heat, so the energy in the sound wave is dissipated and removed from the room.   this is opposed to a glass window, which reflects the sound wave and causes cancellations and reinforcements elsewhere in the room.. 

The very best sounding room I have ever experienced was a very small room in a high end dealership but the room was acoustically quite dead.   The room sounded so much larger and the sound was clear and clean, without confusing reflections in the sound field.  Whatever reverb and echo in the room was what was recorded, not what the room added.  I also believe the dead room killed some distortions from the system, as they would not have as much energy in them as the music itself.  I would treat my stereo room now other than the fact it would never pass the WAF.  

Watch this first, then post any questions. You can see my profile for examples discussed in the video:

This is an hour long video you want me to watch. Can you boil it down please these guys just go on and on and on and on and on

@jumia 

Interleaf absorbers with diffusors

On front wall- Use panels that combine absorption and diffusion (combo panels)

Side walls- 2 D diffusors in front half of the room , 3D in back half

Rear wall- absorbers in center, interleaf 3D diffusors on side

Ceiling- 3D diffusors above and behind MLP

So this seems very ambitious. No doubt it will change the sound characteristics of any room.

Where do you get 3-D diffusers which sounds really cool?

Well I got the ones on my ceiling from Auralex, the Geofusor and T-Fusor can also be back filled with rock wool or polyfil to double as absorbers, Not too expensive either. I hung a Sustain Lens cloud behind the MLP. On the walls I used Auralex Sustain bamboo Pyramids for 3D: