First of all let me put out there that I love the sound of my Mordaunt Short Performance 6, especially in combination with the newly acquired Naim Uniti Nova. However once I experienced what extending the low end can do to the soundstage I couldn’t resist the try… So after some research I got myself a REL T7i. The result was dramatic, even more improvement then the update from my previous amp to the nova to be honest. However so far I have not found a one-fits-all setting on the sub and I get the impression it would be beneficial to have a dedicated cross over between the sub and the speakers. Anyway, I seem to find myself in this rabbit hole of bass optimization now, in which I turned my system upside town and back again several times… 
So here’s my current system:
After many thoughts and losing some sleep over it I finally put this set of requirements together (some seem to contradict each other but who knows…):
- I want to keep the Nova in the system, maybe downgrade to Atom to free up some budget if necessary… (I just love the look and feel and the overall user experience I get with the new Uniti series. I see no adequate substitute at the moment.)
- I don’t want to lose hifi quality, especially in the mids and highs. (The sound stage is well defined and very clear sounding)
- I’d like a way to cross over between the speakers and the sub(s), either active or passive. (I have the REL set to 30Hz but since the MS go almost as far down, they overlap too much, I think.)
- Some room correction in the low frequencies would be nice to get rid of the 40Hz and 80Hz modes I have in my living room. (For that I would need to alter the signal to the speakers low, just handling the sub won’t do I’m afraid)
This is where (after changing it in my head back and forth for a while) I ended up with this idea:
Could this be the best of both worlds or will I mess everything up? 
I’m pretty confident I can get the bass region right but there will be a delay relative to the mids/highs. I have no idea whether this will hurt… If I wanted to get rid of the delay the easiest would be to slap the same DSP and Amp in the upper channel but then I risk losing sound quality plus the awesome novas (or Atoms) amp won’t be used, which would be a shame.
I’d love to hear your thoughts, comments, suggestions on that idea. Maybe somebody has tried this combination? If there is already a thread covering this topic that I didn’t see, I apologize. In this case I’d be glad if you could link to it.
Thanks in advance,
Johannes