@rlross3 I agree with your assessment of B&W Nautilus and the latest Sonus Faber. The older series SF such as Cremona, etc. were dark/warm sounding. But the latest SF are transparent and don’t have the warmth the older SF speakers were known for.
Also, Kimber cables I tried in my system in an attempt to get a bit more air and details resulted in similar experience. The KS interconnects made my system sound bright and fatiguing. Yes slightly more detailed but the cure was worse than the disease.
So if you want to keep your SF speakers, fix your room acoustics and try warmer cables like Acoustic Zen or Cardas. Also give AQ power cables a try.
Lastly, look into a warmer sounding amplifier such as Pass or Luxman. Someone mentioned hearing Levinson with Magico A3 and it wasn’t warm not an indication. The A3 sound like the older Cremona may be even darker.