I bought the Onkyo HT-S780 like many of you. For me, it was after spending so much cash on the Toshiba 72MX195 and to have such a set without the Surround Sound just didn't seem right. Problem is, the Surround L/R and Back L/R Speaker are crap. I had four Bookshelf JBLs in my Studio so I borrowed them and replaced them with the afore mentioned. There lays the difference between sounds good to sounds awesome.
I realize it's kinda dumb to spend cash on these speakers and not use them but if you have JBLs or any other higher quality speakers that you can exchange for the Backs and sides, you will hear a whole new experience with this system.