That would work. But, if I'm not mistaken most Sony's with a fixed crossover are fixed at 120hz. Your M60's can play well below that. I would probably try setting the 60's to large and play the sub as well. I think on the Sony's you would use the "AFD auto" button.

My advice would be, when finances allow to upgrade the reciever with an adjustable crossover down to at least 60hz or get an Outlaw ICBM.