Randy,
I indeed cannot daisy chain my Sony sub to my 600. When I do so, the Sony's output is severely attenuated. When I connect just the Sony, it sounds like it should. I have not been able to establish why this is happening.
At Jason's house, we daisy-chained my Sony to his sub and then to his Denon without issue. And jakeman tells me that he's daisy-chained multiple subs out of the 600. So the issue could be related to my Denon's sub output not being able to handle the additional load or some problem with the 600.
I have to get my hands on another sub to establish where the fault lies.
