I have a pair of Athena S2s as my mains (for surround sys), they are very good speakers, especially when accompanied by a Sub. I use the matching C1 center. But the S2 is a better speaker than the C1 as far as sound quality and power handling. Wouldn't a 3rd S2 be better as a center channel? It would definitely blend better (not that the C1 doesn't blend well) and it handle base/power better.