5.1 to 6.1? 2 sets of L/R rears?

[mercury187]

We moved into our new house this weekend and the living room is a bit rectangular. My old 5.1 setup works great for just having a couch but we were givin a recliner as well. I was wondering if 6.1 would be better or is it possible to plug 2 sets of speaker wire into the same jack on the back of the onkyo 605 reciever? I drew up a photo in mspaint that is fairly accurate of our living room, if I set in the recliner I wont hear anything out of the rear R, not sure if I hear anything out of the rear L, didnt didnt do much testing.

I also placed my sub to the left of the tv, kind of in the corner there, is that probably the best place for it?

Thanks!

Edit: I just noticed I forgot to draw in the front and center speakers, they are just around the TV.