any science to mix and match speakers for HT?


Ardent two channel audiophile wants to create entry-level home theatre. I wanted to create 5.1 system using my 13 year old Thiel 1.5s as front R+L and wanted to know if anyone thinks it is very risky ( for poor final sound) to just buy any decent used mid level audiophile quality center and rear speakers? I already have a decent mid level velodyne sub. Thiel has a rather high end center that is above my budget so I was looking at others.
thanks for advice
idguy
It is better if you stay with Thiels for the fronts, for timbre matching. Look at used MCS or an SCS 2 or 3. Not so inportant for the rears. I want to match mine but at the time they did not make a center channel.
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