Room acoustics: diffusor or absorber?


Hi!
I have Audio Physic Virgo II. in the middle of the room at the long wall, like the Audio Physic recommendation. The listening position is just at the wall.
I treated my room with absorbers (by John Risch homepage) at the side walls, and diffusors behind the speakers with good result.
I do not know what shall I put behind the listening position at the wall: diffusor or absorber, or just leave the wall untreated?
Thank you
norbert2
I have a setup similar to yours and I use three RPG ProFoam Level 1 difussors mounted on foam board. Works great. You can also make your own RPG Skylines clones cheaply.
I made my own skyline diffusers.A 48"x48" for 23.00.They are not to spec but......neither am I. It does involve purchasing a cutting tool for about 30.00 . I'll send you pics and advice if you want.When it warms up I'll take them outside and spray them the color of my walls with a wagner sprayer and some flat gray waterbase paint.The difference in the plain walls and the skylined walls is unbelievable.In my mind room acoustics are the last frontier.Good luck.
Check a thread titled "Diagonal room placement." Rhyno shows how to make the clones.