Having a good mix of absorption and diffusion is certainly essential. Also consider DSP based room correction technologies which operate in the time domain. Dirac Live helps listeners correct for one of the weakest components in the audio chain, the listening room. Dirac Live not only corrects the frequency response, but also the impulse response of the loudspeakers in a room, yielding improved imaging and timbre, better clarity, tighter bass, and less early reflections, as well as reduced resonances and room modes.
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