The rear ambience was really impressive but again makes back wall distance critical. My panels worked great on the cheap I used stryofoam insulation for a backboard with batting material for absorbtion and covered it in needled cotton wrap from Wallmart to match room, I used Owens Corning sheets also, but this way works as good and cheap.
I used on sides in other house but this new room doesnt allow for them so its used for slap echo behind me.