The center should be timbrely matched (minimaly) to the front left/right speakers. Although it's not mandatory for the system to function, it will preserve the reality of the imaging across the front plane.
To assure proper timbre matching, it's recommended thqat you purchase from the same manufacturer and line as the other two front speakers.
On that note, I have the Athena C1 and love it. Of course, I'm prejeduced because it's flanked by a (timbre matched) pair of F1's and a pair of B2's for the rear surrounds.
