Doesn't that setup get a little tricky for controling volume for multi-channel sources ?
Just a suggestion, but you might want to run you pre-out from the PRe3 to the Front left and right 7.1 inputs of the 850, assuming that these aren't already used for SACD/DVD-A. Then leave the Bel Canto at a fixed volume and drive all speakers and the SMS-1 with the Onkyo 850.That way all volumes would remain consistant amoungst the speakers and the 850 could handel the base management. I wouldn't think that passing through what is essentially a pre in on the 850 would degrade the SQL of the Bel Canto.