I'll need to spend some time figuring out what I'm seeing means. I think I have some problems around where the sub and the mains cross which I might be able to better address using REW. It's also possible that the issue has more to do with room modes.
My processor *does not* do everything correctly. In fact, it got crucified on AVS for the bass management. However, I think much of that is tied to the auto-eq. The more I think about it, however, the less it makes sense to split up the processing, especially since I'm not bitstreaming from JRiver to the processor.
I may be a little biased, but I try to do as much processing as I can manage in JRiver. But that's because I ultimately moved away from having a processor at all (I have a multichannel DAC and power amps, so I have to do it in JRiver or not at all).
If you'd like a second opinion, feel free to post some graphs of what you're seeing in the measurements at the crossover. Just make sure that the measurements you post include both the phase and the frequency response (it's much easier to see what's going on if the phase is there). If possible, it would be good to see three things:
1) The sub by itself
2) One of the mains by itself (left only, let's say)
3) And a composite measurement of a sweep that runs through both the sub and the main channel.