Dynamics at lower volumes?

6550c - finally - adherence to a definition - correct. My guess is that what the earlier commenters meant was either (1) that the lowest level of the recorded sound (i.e. the first few seconds of Verdi's Requiem for example) was audible - thereby being able to hear all of the music; or (2) it "sounded" loud (rich, lush, exciting, 'dynamic' or some other subjective term) at low volumes. The first is limited by the acuity of one's hearing. The second was once accomplished by a "loudness button" in consumer recievers (never to be even considered by an audiophile lest consignment to the dungeon). The loudness effect is now accomplished by speakers designed with a non-flat frequency response - so you have the dreaded "loudness button" in all of the time.

Horn based systems deliver clarity, and dynamics at low volume. Some single driver systems are also quite good at low volume. The same can also be said of lower powered triode tube gear, when such gear is also running nowhere near full output. Put the two together and you have the best combination for low volume listening.

I also like electrostatic speakers for low volume listening because of their clarity and ability to clearly convey small volume changes, though they cannot fully benefit from low-powered tube gear.

Efficient speakers + high power SS = dynamics at lower volumes.

I recently experienced this listening to a pair of Acoustic Zen Crescendos and an Ayon CD-2 powered by a Wyred 4 Sound STI-500.

Face - there is something different with class D amps. They tend to play well at low volumes. I noticed it with my Rowland 102 but also read in review of class D amp later. Speakers I use now are 90dB.

Your STI-500 is also Icepower beast.

Tube amps sound better at low volumes because they compress dynamics. My Tact digital amplifier actually sounds more dynamic (a different way of sounding better at low volume) because it has a much better signal to noise ratio than a conventional solid state design.