Right now I have a 5.1 setup with the rear speakers beside the listening area facing each other but about 5 ft off the ground. I'm getting a 7.1 receiver delivered to me (H/K AVR-525) and I was wondering where I should place the rear speakers in the 7.1 setup? I want to keep the other rears where they are beside the couch and I was thinking of putting the two back rears behind the couch on a stand but pointed upwards. If I did that, how tall should they sit? Or is there a better placement I could do? There is no rear wall or anywhere to mount them, so it would have to be something doable with speaker stands. Thanks for the help.