100% room dependent, IMO. My room sounds better with absorption in the front corners. I've done a lot of listening with them and without. I have no option to place them in the back corners as that's in my kitchen ~23 feet from the speakers. There are also panels (GIK 4A absorber/diffusors) in the window wells behind the curtains directly behind the speakers. I've done a lot of listening with treatment/no treatment in every spot around the room.
FWIW, when I was discussing my room with Clayton when deciding which speakers would be right for me, he suggested trying 4-5" inches of absorption behind the speakers with the caveat that it's 100% room dependent...
