Looking to upgrade my back surround sound speakers


I am looking to upgrade both my back surround sound speakers as part of my 5.1 setup. I currently have Martin Logan Spire as my L/R and the Martin Logan Encore as my center channel. Any suggestions? Should I keep with the Martin Logan brand...do they make dipole/bipole/monopole speakers?

I have a beam about 10 inches behind the listening area and a wall in which I would mount the rears. I prefer not to dig into the wall and thus prefer mounted speakers.
pig2fever
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I'd go with ML, too. This will keep the voicing the same throughout the system, very important for a seamless flow from front to rear...

-RW-
I would buy some used script i's. Those were fantastic srrounds and I love the design.
Dont get crazy on this idea of voicing for rears surrounds as noted its not exactly in your face sound. The content will be ambient, add space and depth with some affects mixed in. There is no need to be anal about them, as long as they are in the general ballpark you will be just fine.
I used B&W surrounds with Innersound Eros so I speak from almost exact experience. Also at that distance its questionable as to the need at all but I would do it if thats what you want, just place them high on wall so the dont call placement attention to themselves.