One thing I would add to the above addendums to Stehno's advice concerns his recommendation to place the speakers at "the long end of the room". This phrase is somewhat ambiguous - does he mean "along the long wall" or "firing long-ways down the room", which means placed along the short wall? If the room size allows you to sit the correct distance away from a conventional monopolar dynamic box speaker without the rear wall being too close to the listener's head, speaker placement along the long front wall may be best, as it places the speakers farther from the sidewalls, avoiding early reflections (some actually recommend positioning the listener's head close to rear wall with acoustic treatment behind, but this will boost the perceived bass). For dipole panel speakers, which have a figure-8 radiation pattern with nulls to the sides, placement along the short rear wall would be better, so as to allow the speakers to moved as far out from the rear wall as is practical, and allowing them to be relatively closer to the side walls. For small monitor-type box speakers designed to be listened to in the nearfield, set-up whichever way is best so as to allow both the listener's head and the speakers to be farthest from room boundaries. Also, though strategic placement of bookcases, draperies, etc. could somewhat ameliorate the need to invest in acoustic treatment, if I was doing a dedicated room from scratch, custom-built to the correct proportions etc., I wouldn't skimp on checking into purpose-made treatment systems, or even hiring a professional consultant from the beginning. I've heard a more startlingly real, holographic image cast by a pair of utilitarian self-powered Mackie small monitors precisely positioned in an acoustically designed and treated studio control room (no parallel walls, angled ceiling, staggered sides, absorptive and diffusive surfaces), than I have ever heard from any high-end system in a normal room. At least consider treating the ceiling first-reflection points if all the rest is too extravagant. One more thing: if we are talking ground floor, you may want to consider having slab concrete below the carpet at least at the end that will be underneath the speakers and maybe the equipment stand, especially if there is a turntable involved.
