The listening room contributes as much to what you hear from your system as any of its components. Fortunately, the typical home listening room is usually friendlier to good sound reproduction than a large hall or theatre. A family-size audience means low background noise. Typical home furnishings help prevent echoes and reverberation that could muddy the dialogue. And it is both easier and less expensive to achieve wide frequency range and ample loudness with low distortion in a living room than in a large public place.
Room characteristics that contribute to good hi-fi music reproduction are just as appropriate for good home theatre sound. Carpeting on the floor and drapes on large picture windows will cut down on mid- and high-range sound reflections that can add harshness to music or muddy the dialogue. If you have the luxury of choosing among several potential sites for your system, avoid those rooms that have any two dimensions the same (such as a square room), or that have any one dimension exactly twice another (such as a room just twice as long as it is wide). Such dimensions aggravate "standing waves," low-frequency sound resonances that in some cases may color the sound.
Arrange the seating area so that it is centered between the side walls on which you mount the surround speakers. Speaker systems mounted in walls or furniture may require extra sealing, baffling, and/or damping to minimize reflections and refractions that could color the sound. Any cloth used to hide speakers must have a weave that is "open" enough to let high frequencies through. And of course, you should prevent other furnishings from rattling or vibrating on strong bass notes or sound effects.