Diffusion versus absorption behind speakers?

I didn't really find it expensive and I am far from a "cost no object" audiophile. Your room is THE MOST IMPORTANT COMPONENT in your system, if it is bad nothing else matters. I sit in the same place now, which is close to the speakers, that I sat before I treated the room but the sound is very different. Improved? In every respect. If you haven't dealt with room reflections you have no idea of the way they blur the sound. I didn't. If you can try out some good headphones on your system to see what it sounds like without your room interfering. No, headphones and speakers do not sound the same, but you will still get some idea of whatever problem exists. I spent around $800 on my room, could have been less if I had used their DIY option, and there is nothing else I could have done for 4 or 5 times the money that would have given that improvement. My listening friends share the same opinion. Try the furniture by all means, as well as rugs. The wall to wall I inherited when I bought the house turned out to be useless in light of the improvement of the Costco wool area rugs that replaced them. I also had the walls lined with 2+ tons of books and my 3000 LPs and that did not cure the reflections.

I have tried rugs, curtains, furniture etc as "room treatments" but in general I did not find significant improvements. Professionally made acoustic treatments (ie, GIK, RealTraps, etc) are designed (with measurements done in certified acoustic labs) to cover appropriate frequencies and are very effective. In my experience, furnitures, books, rugs, etc are crap a shoot and are less than satisfactory unless you have glaring acoustic problems (eg, room with extensive glass windows) in which case some minor improvements can be heard. Yes, some professional stuff are very expensive, but there are some (eg, GIK) who sell reasonably priced treatments.

But let's get back to my original question regarding room treatments behind the speakers. I don't mind if you mention specific products as long as you are not selling them. Thanks.

Some say that 60% of what you hear from your system is your ROOM.

I was told to try some wool carpets or blankets behind my speakers to keep my downstairs neighbor happy. I tried some thick 2.5' X 3' cotton rugs behind my speakers and she can't hear a thing now. If it can keep the sound from running down the walls (and I do play it loud at times), then one can imagine how it 'tames' reflective sound.

I've tried both absorption and diffusion behind my speakers at the front wall and in the end removed them and now don't use anything behind them. Instead, the corners are treated with bass traps, the upper corners with Eighth Nerve triangles and the seams where the ceiling meets the wall with Eighth Nerve rectangles. Unfortunately Eighth Nerve is no more, but their concept on how to treat rooms is very effective for me.

As previously mentioned one can eliminate many room interactions by listening near field, which due to my room configuration is really my only option. You might also want to post this over on AA. There are some great resources over there, especially David Aiken, who have helped me address this issue, especially the best methods to use diffusion.