Just a few ideas.
I am new here, but I am not new to audio. Just a tinned ear hobbiest.
Sorry for a long winded answer, but I like long winded answers.
There is a lot of information on this site regarding room reflections.
http://www.audioholics.com/techtips/roomacoustics/index.php
If you were to place a mirror on the side walls, there is a point that you could see the speakers from the sitting places on the couch.
That is a first order reflection. Mean, ugly sound comes from that point. Actually what is happening is that the speed of sound is slow enough that the reflective sound is reaching your ear at a time interval that is long enough from the original sound reaching your ear, and you become confused by the sound. It is a time delay issue, much like the sound of a gunshot bouncing off the surrounding buildings that causes you to misplace the direction of the gun shot.
First order reflections, even minor first order reflections, to my ear, cause the sound to "sound" hollow.
There are second order reflections from other points, such as looking into a mirror on the right wall, and seeing the left hand speaker.
Second order reflections are not as powerful as first order reflections, something to do with physics and sound energy.
Third order reflections in theory also exist, as would fourth order reflections etc.
The best solution is absorbtion and dispersion.
I have a thing for bookcases. Lots of bookcases. Loaded with stuff and lots of books.
Bookcases, or similar materials, placed at first order reflection points solve two problems. Books and other such materials (like my teddy bear from when I was a child) absorb sound waves. Absorbtion is good. The other stuff reflects the sound. Yes some of the reflections may still reach your ears. But not all of the reflections, and those that do reach your ears have bounced around the objects from the shelves and become diffused, thus becoming second, third, fourth etc reflections.
There are DIY projects using foam materials and the such to create sound absorbing panels.
You can also use decorative rugs and blankets hanging as wall decorations.
But I like the bookcases. Clean. Simple and very WAF. And a good backing to the bookcase can reduce the amount of sound that may pass through the bookcase and sheetrock behind the bookcase.
Surround speakers usually like reflective point to develop a wide, spacious sound field. If you are using basic speakers for the surrounds, let the sound bounce as much as it pleases, though I could see a problem with the RS bouncing sound off the closet.
The carpet should reduce the first order reflections from the concrete floor to your ears.
If the carpet is insufficient, try adding a decorative throw rug in front of the speakers. It could be WAF friendly and solve the problem.
The ceiling is a problem area. But it is usually not a big problem. Try the mirror test, and try to determine the first order reflection point. I personally cant find the point in my room. I know that it exists, but my arms just are not long enough to hold the mirror to the ceiling, and sit in my chair to find the reflective point.
In my room, I solved the ceiling problem by adding a ceiling fan with a big fancy light fixture. What ever sound is hitting the ceiling is being bounced around from the fan and lights. If the ceiling is a problem, you will need to try some of the DIY foam panels.
