The bargain/high value approach is a combination of Owens Corning 703 acoustic panels and Synergistic Research HFT. OC703 is cheap and easily cut to size with a knife, then all you do is wrap with fabric and presto, $500 acoustic panel for $20! This material is absorptive and very effective so a little goes a long way especially if used in the corners like this https://systems.audiogon.com/systems/8367
HFT don't work like conventional old school diffusers but they do make a huge improvement in clarity, detail, and imaging. The ones made for speakers and the ones made for walls all work the same, so if you don't want them on the walls you can still do the speakers.
HFT don't work like conventional old school diffusers but they do make a huge improvement in clarity, detail, and imaging. The ones made for speakers and the ones made for walls all work the same, so if you don't want them on the walls you can still do the speakers.