I have tried so many speakers since the original Allisons, designed to be placed against the rear wall and the ones that work best are North Creek Kitty Kat Revelators. They are designed specially for rear wall placemat and they will fill your room, even tho they are monitors. Call Rob at northcreekmusic.com and talk to him. They make a floor stander, too. I don't know about the corner, tho, which is why you should ask the designer.
They sound great and probably don't need a sub.
I gave no connection with this company, btw.