I agree with the other posters that it depends on your room. I also agree that you should experiment.
Personally, I've tried both absorption and diffusion between my speakers. I prefer diffusion by a considerable margin. In my case, absorption resulted in a significant increase in clarity, but at the expense of decreasing both the size of images and the depth of the soundstage. Diffusion suffered from neither of those problems, and provided 90% of the gains in clarity that absorption provided.
IME, getting the balance of absorption to diffusion right is a critical, and often overlooked, determinant of sound quality. In addition to the expected effects, like resolution, coherence, imaging, etc., the ratio and location of absorption/diffusion is also a major factor in creating the illusion that "You are There."
Bryon
Personally, I've tried both absorption and diffusion between my speakers. I prefer diffusion by a considerable margin. In my case, absorption resulted in a significant increase in clarity, but at the expense of decreasing both the size of images and the depth of the soundstage. Diffusion suffered from neither of those problems, and provided 90% of the gains in clarity that absorption provided.
IME, getting the balance of absorption to diffusion right is a critical, and often overlooked, determinant of sound quality. In addition to the expected effects, like resolution, coherence, imaging, etc., the ratio and location of absorption/diffusion is also a major factor in creating the illusion that "You are There."
Bryon