Thanks to mojave and Matt for replies! Double that because it's holiday season.
I am hoping for a little more clarification. I've read all your answers twice, but I'm still missing this: what is different when I turn JRSS on vs. setting Channels to 2.1?
In both cases, I'm using Bass Management, with a high-pass filter for the mains and Routing (a low-pass filter?) set to "Move bass to subwoofer."
I understand the two approaches (JRSS vs. 2.1) can sound different -- in my case they seem to -- and I'd like to know what they are doing, so I can understand why.
I have used electronic crossovers, and MC seems more flexible than the hardware-based approach, but it's not clear what it's doing behind the curtain.
Thanks! And all best wishes for the season.