Everything I have read has stressed getting voice-matched speakers when building a 5.1 speaker system. Does this make it impossible to build a system in steps. For example, you started with a stereo pair. Then several years later, you wanted to add a center and surrounds for 5.1 capabilities, but find that the line has been changed, or find some better option from a different line or manufacturer. How noticable would the lack of voice-matched speakers be.
What I'm asking is how much of a difference can you hear between different speakers in a 5.1 speaker system.