Absorption, Diffusion or a combination of it all?

I’d definitely recommend either quadratic diffusers or something like GIK Alpha panels. The latter have the advantage of providing both scattering and some bass trapping, if you get thicker ones.

For what it’s worth, Paul McGowan prefers diffusers to absorbers; the former mix reflections of all frequencies equally, while the latter absorb different frequencies to different degrees. McGowan also explains that the reason “first reflections” cause problems for imaging and soundstage is that they arrive at the ear “too quick for the brain to sort them out as delayed copies,” so they muddle the spatial effects of the perception of the direct sound.

It's easy to make a diffuser. Go to Home Depot and buy a long, square wood pole. Using a skill saw, cut it into lots of small cubes with angled cuts. The angles don't need to be precise or the same, nor do the cubes need to be the same height. In fact, the diffusion pattern is actually enhanced by irregularly sized and shaped pieces. Softer woods absorb more than harder woods, but either will work. Then glue them, flat side down, onto a board of the size you need. If you want to absorb some lower frequencies, glue them onto an acoustic ceiling panel (also available at places like Home Depot). Works well and looks good, too.

This very absorbing conversation may confuse you on diffusion.

Most say behind speakers you diffuse.

If you build Snifle's diffuser keep in mind it will be heavy!!!

IDK who Paul McGowan is, but does he have any science to back up his claims about sounds arriving "too quickly" for your brain to sort them out?  

Also, do you have any evidence that can be replicated that softer wood absorbs more sound than harder does? If that's accurate (and it's not) what happens to the softer wood after is absorbs all the sound it can hold? Does it explode? Does sound start leaking out? And if it's saturated with sound, wouldn't it then be unable to absorb more sound and revert to the hardest wood ever grown? 🙄

Or, don't bother with either and simply enjoy music with a bit of room sound.