Diffusion versus absorption behind speakers?

Thanks everyone for your responses. I am not a novice on this subject. I know treating corners of the room and back wall behind the listening seat with bass traps has beneficial effects to tame room modes. Also treating first reflection points help in imaging. But I have a specific question regarding the front wall. Some use absorption that helps with better pinpoint imaging. Diffusion, I heard, makes the sound stage bigger but images get larger also. I probably will end up with a box speaker and a panel speaker. So I'm trying to to see which front wall acoustic treatment will help both types of speakers. I get the feeling absorption behind dipolar planar speakers may not be a good idea.

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.

Thanks Clio. I think your approach is making more sense to me. Leave the front wall alone and treat the corners of the room and possibly side wall first reflection point.