Well a while back at HTT it was determined by many folks that you MUST have the same brand surround speakers in a HT set up to get the most/best/coherent sound throughout. To catch the folks up who missed out, I run the same brand speakers (Celeston) on my front set and center..the 3 rears are Optimus bookshelf speakers..I don't recall the model number. Well after the discussion I started paying more attention to the sounds I was hearing...one test that I hadn't planned on was done while watching "Monster House" there are several scenes that are great at showing off any discrepencies in tonal sound etc between fronts and backs... One scene is early on when the red headed snooty girl rings the doorbell of the main kids house to sell the babysitter some cookies...in the scene the camera pans around while the doorbell rings numerous times...the sound travels from the front (showing the door) and rotates to the back surrounds while the scene adjusts the vantage points of the scene..it is very easy to hear the lingering sound of the bell as it moves in the scene. I can safely report that not one time during the sound panning did I notice even a tiny bit of change in tone of the doorbell...it consistently sounded the same the whole time. There were a couple of other scenes that offered up such "tests" and glad to report they all passed with flying colors.... I still keep my ears open when we watch movies to determine if indeed not having the same brand speakers for the rears is ruining my experience, but so far, using a different brand set of speakers has had ZERO effect on the movies.