I caution against comparing tube, linear solid state, and switching amplifiers. Each has its own set of virtues that the others can't quite match and that class D is simply a third choice in amplification. On the other hand reading about the Bob Carver challenge gives one pause.
Assuming that everything in the chain contributes, in my experience low volume dynamics is more a function of the speaker design. Most of the contributors above have evolved with class D. For me beginning with the PS Audio HCA-2 a few others then the NuForce SE class D has been the most responsive to power and cabling. The nCore 400s are another step forward that I can only describe as more of everything which would make the NC1200 yet another level that is better described by Larry Greenhill in his Theta Prometheus review of the Hypex 1200s ability to handle high rail voltage.
Assuming that everything in the chain contributes, in my experience low volume dynamics is more a function of the speaker design. Most of the contributors above have evolved with class D. For me beginning with the PS Audio HCA-2 a few others then the NuForce SE class D has been the most responsive to power and cabling. The nCore 400s are another step forward that I can only describe as more of everything which would make the NC1200 yet another level that is better described by Larry Greenhill in his Theta Prometheus review of the Hypex 1200s ability to handle high rail voltage.