Dynamics at lower volumes?

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.

Gain matching improves signal to noise ratio (which is right next to Godliness).
A simple resistor on the "hot" side of the amplifier input is all you need to do it correctly.
Here is how you can determine the value you need:
1. buy a few cheap resisters: (say two pair of 10K pair of 5K pair of 1K)
2. take a pair of junk interconnects, cut them in half and solder (or alligator clip) the 10K across the center wire and then reconnect the shield/ground side to complete the circuit. If 10K is not enough add more. When you decide what value resister you need, you can buy low noise Vishays or Caddocks from Parts Connection and solder them in. (When you sell the amp, just remove them.)