Quote Originally Posted by kexodusc
I've had mixed results mixing and matching centers to front mains.
Short story - if the center is of higher quality than the mains, it's usually pretty easy to integrate - the only question is the presentation or voicing, how well does it mix? If it's really bright and the speakers are very warm, it's probably not going to blend well. If they're close at all though, you can get away with it and have things sounding pretty good.

If the center is worse, I find it sounds terrible.

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I agree on this point totally. My situation is like that with my DIY BGC/Vifa center and Paradigm MiniMonitor sides: quite livable. What is unfortunate is that there is a seemingly natural tendency for people to buy much better sides. This might work if you listen mainly to stereo music, but otherwise not.