I understand that rear speakers should be placed to the side and not the back but with the space limitations I have to deal with, I am thinking of mounting my rear speakers (Logitech Z-5400) to the wall behind my couch. Speaker stands would get in the way because behind the couch is the bathroom door. Would it be okay? Would I still experience the surround sound? I'd like to hear from people that have got a similar setup before I drill some holes into my wall.