pulling speakers off the back wall can sure help!
speakers have always been away from the wall and a few posts before yours, i had mentioned that the speakers are now 30" from the back wall.
The best I had was using bass traps in all corners, but my wife made me remove them because they were "Ugly". I tried to pain them white, a very bad idea. Buy white ones, they are said to yellow after a time, but still my recommendation.
as mentioned in the beginning.....i have GIK acoustics and do have corner bass traps already.
after moving the speakers and adjusting the subs, had the wife listen last night to a few songs and she says that it sounds like the singer is right there, which again , is just the center imaging is there and there are times you can hear / vision something behind the speaker, like a cymbal but that is it.