Ask any acoustician what the single biggest factor in how a system sounds is, and the answer is almost never the equipment. It’s the room. A modest pair of speakers in a well-treated space will consistently outperform an expensive pair fighting bare walls, hard floors, and bad placement, and yet room treatment is usually the last thing anyone spends on.
Placement before treatment
Before buying anything, move the speakers. Pulling stereo speakers away from the wall behind them, even by a foot, reduces the boundary reinforcement that causes boomy, undefined bass. The classic starting point is an equilateral triangle between the two speakers and the listening position, angled slightly inward.
Symmetry matters more than most people expect. A room where one speaker sits near a hard wall and the other opens onto a hallway will produce an unbalanced stereo image no amount of equalization can fully correct.
The cheap fixes that do the most
Hard, parallel surfaces — bare walls facing bare walls, especially with a hard floor — are the main culprit behind harsh, boxy sound. A rug on a hard floor, curtains over a large window, and even a bookshelf densely packed with books at ear height will absorb and diffuse reflections meaningfully, all without spending a cent.
The best acoustic treatment most people own is already sitting on their bookshelf.
The first reflection points — the spots on the side walls where a mirror held up would show you the speaker from your listening position — are the highest-value places to add absorption if you’re going to buy foam or panels at all.
Bass is a different problem
Low frequencies build up in room corners and create uneven bass response that changes dramatically depending on where you sit. A subwoofer’s position matters more than its size for this reason — crawling it along the floor to find the spot where bass sounds most even will often solve problems no equalizer can fix cleanly.