I noticed that you posted that one speaker is the same distance from the back wall as it is from the side wall. Am I correct to assume that your speakers are not set up from the center of a wall, and the speakers have different distances from rear and/or side walls. As your set up is in a square room, having the same distance from side to rear is compounding that problem. If each speaker has a different distance from the rear wall you might have slight inequity in bass response. If each speaker, has a different distance to side walls you may have image shift or even a spectral discrepency where one side may seem brighter than the other. Perhaps you can describe the positioning of your system and your listening position. May I humbly suggest playing with an unorthodox set up, where your listening position and system is set up diagonaly across the room, where your speakers would both have the same distance from the slanting rear wall and the same (but different from the previous distance) from the slanting side walls. This would allow your video monito to be placed further back from the plane of you speakers (good) and might facilitate another Spica TC50's proper equidistant set back for a center channel (good). There may be some other advantges that due to the fact I'm only guessing at, I'll keep to myself. Play with this before purchasing that center channel. This may make things sound better. Of course it may make things sound worse.