I had a similar experience to the OP breaking in a pair of Harbeth 40.2 Anni's. I solved the problem by positioning GIK 244 free standing panels parallel to the side and in front of each speaker, which addressed the first side reflection points. While I no longer need or use the free standing panels, they did successfully solve a problem while my speakers were settling in. If you are within driving distance to St. Louis, the GIK panels are available.
Warm Tube Amp(s) to Tame Hyper-Accurate Speakers?
I have these Spendor D9.2's mated to an MC275 VI and the mids and highs are still too much, sometimes. Sometimes the sound is sublime based on the recording, sometimes harsh. I imagine perhaps Focal and B&W folks know what I speak of, maybe not Magico owners. Even using a C2700 tube pre-amp. Can this be solved with a WARM tube amp, and if so, which ones? I like my MC275 VI but I am open to suggestions.