Speakers for low-level listening

This has been covered many times before. Using what equates to little more than a loudness button is antiquated thinking.  Ultra-sensitive loudspeakers, often horn-loaded, are more dynamic. Dynamic range at all volume levels, including at low levels, is higher. The human brain perceives increased dynamic range as more satisfying at low listening levels. You yourself already wrote;

I previously had Klipsch Cornwalls and found them very enjoyable for low level listening

So, I have to ask, haven't you already answered your own question?

I really like Harbeth 40.3 or SHL5XD for low to moderate listening volumes.  I had Focal Scala Utopia EVOs and prefer the Harbeths for moderate volume listening. 

@fsonicsmith wrote:

This has been covered many times before. Using what equates to little more than a loudness button is antiquated thinking.  Ultra-sensitive loudspeakers, often horn-loaded, are more dynamic. Dynamic range at all volume levels, including at low levels, is higher. The human brain perceives increased dynamic range as more satisfying at low listening levels. You yourself already wrote;

"I previously had Klipsch Cornwalls and found them very enjoyable for low level listening"

So, I have to ask, haven't you already answered your own question?

I definitely agree with regard to high sensitivity speakers usually coming better to life at lower SPL's vs. low sensitivity, passively configured and direct radiating speakers with dynamic, i.e.: voice coil- and cone-fitted drivers.

What accounts for and are the mechanisms behind low SPL acuity is less clear to me however. A more or less educated guess could be that the actual horn-loading with its gradual diaphragm/cone to air coupling from high to low impedance is part of the explanation, as is the higher ratio of direct vs. reflected sound meeting the listener. Added to that is less inertia build-up in the cone or diaphragm with more (effective) displacement area and less movement for a given SPL, which reduces smear and, at least as an outset, leads to a gain in clarity. Connected to this can be better rise/stop time and transient abilities/micro dynamics (perhaps that's what you alluded to with your mention of "dynamic range"?).

Sitting in front of a large displacement area and high sensitivity, tall speaker system, certainly as heard from my own setup, clearly gives way to a more "attentive" feel for the music at lower SPL's vs. a low sensitivity and smaller speaker system, and that's despite of my main speakers being ever so slightly rolled off in the upper octave (soon to be alleviated with a pair of JBL 2405 Alnico supertweeters), which is due to large format and 2" exit compression drivers that are naturally bandwidth restricted in the upper octave. 

To the OP: I'd definitely consider and even strongly prefer the suggested AK6 Klipschhorns given your stated preferences. 

I use Focal Utopia headphones for late night listening at realistic levels. They are incredible.  I regularly listen to two systems (one on the house main level and one on my walk out basement level).  The upstairs system is a BAT VK-33 preamp with a BAT VK-76SE power amp and Focal Electra 1037 Be speakers with matching Focal SW 1000 Be subwoofer.  The downstairs system is a BAT VK-31 preamp with a BAT VK-600SE power amp and Legacy Focus SE speakers.  The Utopia headphones are a great alternative for late night listening when I want to keep my wife happy! 

BTW I use a Musical Fidelity MX-HPA fully balanced headphone amplifier.