It's really funny that absolutely no one knows the definitive answer to this. We should write a letter to one of the designers/engineers at one of the major receiver companies.
What's even more funny is that no one can tell by just testing it out and listening. That should be the easiest way to figure it out. Of course, it probably makes absolutely no audible difference, so we can't figure it out that way. That brings up the point again about this question being pointless. If nobody here can actually hear the difference, who cares? However, I'm now interested out of curiosity and I think we should write a letter to solve this if nobody here can provide a sufficient and definitive answer.
I bet you most modern digital receivers just digitize the analog input when applying bass management.