I have the B&W DS6 as rear surrounds now, with Martin Logan Aerius at the front. My question is, should I be using two more DS6 in the rear for 7.1 sound, considering also that they are a dipole speaker. They would be 4 feet behind and 7-8 feet in the air...no other choice. The rear ones are currently 6 feet in the air and 1-2 feet behind listening position on the side walls. Thanks.