The 950 has a single center pre-amp output, so you would want to put a splitter on it for the two center channels. The dual centers with 100W each would probably work best if the Mission 732's are used, as they will presumably be a closer match to the 765's you have as mains. I don't know how efficient those speakers are (couldn't find anything online), so I don't know whether the Adcom will keep them happy or leave them hungry for more -- it's very possible that they'll do just fine. If not, you could try swapping the 545 and the Mac; the 545 should be more than capable of driving the JBL's in a surround role. The only possible issue there might be sonic differences between the Adcom and Mac across the front soundstage, but I don't know enough about your amps or your preferences to know if that would be an issue or not.

Oh, and welcome to the Outlaws. If you want to get a jump on the arrival of your 950, you can grab a copy of the manual online (as you may already know).

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review