Bryston 3b or adcom 100wpc for center & main

I have a HK 635 with infinity crescendos for mains,thiel center and mirage surrounds with svs powered sub.The surrounds are powered by an adcom GFA 2535.My question is do I power the mains with the bryston or put it in mono for the center and use the adcom 100wpc for the main?
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Would there be an advantage to using a stand alone amp for thye center channel instead of the internal amp in the HK? I had been using a sony amp in mono mode in the past without a problem.
Mixing 3 amp brands and 3 speaker brands is not a good idea. Consider selling your least favorite amps and speakers and start building a proper system with matching speakers and amps. Start with the center or L&R speakers.