As a follow up, after 100 hours or so the Stirlings have calmed down quite a bit. Still tough for moderately long listening and I'm pointing my finger at my source....although the same defect is true with both my digital and vinyl. Finding time to play at moderately loud volumes is a little hard around here, so break in is slower than I'd like, but Acoustic Zen Hologram II biwire helped (they are breaking in as well). I've been able to move the treble energy to -1.5, so that's moving in the right direction anyway. They are more musically involving (for me) than my Devore which seemed to check off a lot of boxes and were much better in many ways, but left me at a distance. An audio friend described them as "fauve" and I think that fits.
I'm going to stick with this for now and am considering a full reconstruction back to SS and inefficient speakers - like Gamut or Plinius power and Supratek Pre driving Dynaudio Confidence 3 or 5. That's my most familiar ground and sticks in my memory as a sonic delight.