The sony Str-db1080 is a 6.1 dd ex/dts-es amp. 1. Is it possible to add a second surround back 8ohm speaker in series with my existing 8ohm speaker as the amp only allows for one. 2. Is it possible to do the same with each of the surrounds eg. making the sound field, surround left1, surround left2, surround right1, surround right2. I am asking these questions as my living room is 25 foot long and i would like to be able to fill the void down the side walls.