There was an intriguing post a couple of months ago on either avsforum or hometheaterforum on deriving two top channels. It was from "Greg" (not me). The theory behind it was a bit obscure, but it seemed carefully tested. A left top signal was derived as the center channel of Dolby matrix decoded right front and left side surround, and a right top signal similarly, from left front and right side surround. Greg used two Smart Devices CS-3X jr. from smartdev.com. Sorry that I didn't save a link to the discussion thread.

So, if you really need 9.1 now, ...


Greg
VP180, M80s, M22s, QS8(4), CSW S305s, EP500, Pioneer VSX-90
M2i, M3(2), Pio vsx-1020