I would get the small and cheap HTM-200 SE Ascend surrounds if you have Sierra towers. I have three CBM-170se's that have been sitting in my closet for years. Tried to give them away with another sale but buyers were not interested. Moral of the story, some gear you will be stuck with, rear channels are not very important outside of timbre/level matching. Go with the cheapest possible, because like me, you could have them in the closet for 3-4 years. Caveat, I went from 5.1 down to 2 or 2.1 even for movies, just my preference.