ottopookey, (geez, I feel funny even typing that), I just went through a situation with my center speaker. I got new Front L/Rs, and the center was from my old set. I'm gonna buck conventional wisdom a bit here. For TV/Movies, I could not notice a mismatch, though the old center is WAY different than my new L/Rs. TV still sounded fine, and movies still sounded fine.
However, there was a HUGE difference in music, using only the L/Rs. The new speakers were amazingly sharper and more clear. So I began to wonder. Maybe a new Center from the same manufacturer would be equally more sharp and clear with voices than my old Center. Sometimes my wife and I have trouble understanding dialog on TV/Movies, so maybe sharper and clearer will help. So I just ordered the new matching Center.
My point is that I never watched TV or a movie and thought, "Oh my!!! That center speaker doesn't sound right with those L/Rs." So while I understand all the timbre matching stuff, I'm not convinced a "mismatched" center is really that big a deal. To me, the big deal is clarity for voices, which is the main use of the center speaker.
So if you think your Center is not clear or detailed enough, by all means look for one that is. You can find a very inexpensive one here:
http://philharmonicaudio.com/aa.html
So far as matching your other speakers, I wouldn't worry too much about it. If you get a center that is clear, crisp and detailed, I don't think it will be a problem... other than perhaps encouraging you to upgrade your other speakers at some point. "Wow!!! If voices sound so clear through this center, I bet music will sound as clear through better L/Rs."
