Hello, Allan.
As it happens, I spend much of my time listening at low SPLs - because my wife can't concentrate on her tasks if the music is too loud, and because I suffer from hyperacusis in my right ear. [Encouraging my wife to go shopping every day results in fewer funds for my audio hobby 
Hyperacusis is <somewhat> treatable with pink noise therapy or a knowledgeable acupuncturist.] I haven't bothered to measure my listening position to my speakers in ages, but I think it's ~10'.
I still haven't posted my review of this amp, but I can tell you I really like it. I haven't switched back to my much loved KT88 amp since the Nuprime amp arrived. My sole complaint about it is that <unlike my KT88 amp> it doesn't heat up my listening room during the winter. 
Michael
Greetings Michael. Many thanks for sharing your experience. I appreciate it. I returned to edit my post to characterize SPL preferences but was happy to find your response.
To SPL I should say I need to keep the volume down for reasons similar to yours but, for critical listening, absolute numbers are less important than life size SPL. Single, close mic’d front row acoustic guitar expectations are different than mid row concert hall symphony.
Besides a 60 year old back, the inefficiency of a full time 200W space heater is the primary reason I hesitate to jump on Class A. A west facing room in the middle of a NC summer is uncomfortable enough. I’m also both a cheap SOB and (more than) a bit irrational. I spend more on LED bulbs than we’re ever likely to save in electricity usage but I’m an engineer who’s obsessed (to a fault) with efficiency.
So the more I think seriously about amps the more I consider the value in finding that just right combination of performance, efficiency, and what I can only describe as topographical artistry.
In my limited experience I believe many Class A or A/B designs are owned end to end by the designer and reflect their values. Class D seems to be a relatively new art form with most designers choosing a paint by numbers approach. Constrained by the same picture, they’re left with primary color selection being their most significant differentiator. Perhaps this is an overly harsh and ill informed characterization and genuinely unfair to those who passionately labor in this art form. If you are one of those or one of their adherents please accept my humble apologies. I mean no disrespect.
Perhaps it’s premature for me to consider this, but what little I’ve learned about NuPrime in the past few hours suggests they are to Class D what someone like Nelson Pass is to Class A - at least in values. Bruno Putzeys and others will certainly come to mind but I’m thinking only of end to end design.
