My suggestion would be to buy a receiver that has "zone two" outputs and run that line into a multichannel amplifier designed for the function you want. You can manage ten speakers with most well designed receivers by using autoformer type switches or volume controls; but the multi channel amp will give you better sound and better control of the system at about the same cost if not slightly less money.
Where are you going to have the speakers? are you going to be running 6.1 in one room then pairs of speakers in 2 other rooms? Do the different pairs need to run off different sources?