Absorption or diffusion? Neither.

One school will tell you to go full absorption. The other will tell you to go full diffusion. Neither is correct.

Each room has its own properties, and you address them one piece at a time. Here's what finally worked in mine: absorption panels across the back wall and on parts of the front wall, with acoustic diffusers positioned carefully among them. Not a philosophy, a combination, found by trying.

My seat was very close to the back wall, so the first reflection points were my biggest problem, and that is where I started. The first round had a budget of no more than $500. One panel or one diffuser at a time, moved between positions and measured before the next one went up.

The bigger risk is not choosing the wrong school; it is overdoing either one. I have done it myself, more than others. Too much treatment and the room turns lifeless, and every dollar you put into speakers and gear ends up playing into a space with no air left in it.

Treat the room you have, not the theory you read. And stop one panel earlier than you think you should.