Dynamics at lower volumes?

Elizabeth. You are gain matching. Try using the passive after the preamp instead of before.

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.

1. Speakers need a very good signal to noise ratio. Eectrostatics, for example.
2. Tubes compress dynamics. This acts as a loudness control at low volumes giving the impression of greater dynamics. The ear is most sensitive in the upper midrange and the least in the bass.
Short answer, listen to some Quads and some very quiet tube amps.

Peter Walker (Quad) maintained that every recording has a specific volume at which it sounded best. Loudness controls are band-aids at best. I use a digital dynamic loudness control that I can program as I wish (a Tact DRC program). It is enjoyable, but does not restore what has been lost by using the "wrong" volume.

Peter Walker's unorthodox opinions are well worth studying. He did not believe in flat speaker response (try his roll off formula by using, say, Audacity to burn an equalized CD). He designed his speakers not to image in the listening room, but to approximate the sound of music coming through an open window.
My favorite was his comment when asked how far our hobby had come towards the actual sound of music. He snapped "about 15%"!

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.)

OK 6550c, Trelja, define your terms. I will venture that reproducing the dynamic range of "real life" in the home is impossible.
What we actually do is play recordings that have a very limited dynamic range.
The question posed was "Are there are any speaker or amp designs that are thought to generally be inherently better at producing good dynamics at lower volumes?". The answer is that some designs are more liner at low levels than others, and that some designs are perceived as such, even though they are not. This question is related to, but not the same as the question of how we perceive sound through our ear/brain. Cheap loudness controls and speakers with depressed midrange response are certainly to be avoided. The DRC that Tact uses is quite sophisticated and can be user adjusted to conform to any set of curves one wishes.