Hey, Hoots! No need to upgrade beyond your 1050 (unless, of course, you want to do so). You can hook both speakers up in parallel to the BC channel on the 1050 (the owner's manual even says so!) without any trouble. Unless you want some different processing options or more power, I would just do that.
The 7.1 setups are, to the best of my knowledge, not really 8 discrete channels but rather seven. I believe the the same mono signal is sent to both back channels so there would be no difference (from a signal viewpoint) to have the BC paralleled to two speakers versus a setup with two seperate outputs.