Full detailed sound at 30 - 40 - 50 dB


I love the nuance you can hear when listening to music at loud volumes, but unless no one is home, it’s not considerate or feasible to listen at such high volumes. Plus I just had a baby so everyone is always home and volume levels are limited to 40ish dBs. 

Any recommendations for getting the most detail at these volumes? Additional gear or recommended integrated amps?

My NAD 7175PE has a loudness button which boosts the treble and bass a little, and that certainly helps things in the Kitchen. 

My living room amp is a Rega Brio-R which doesn’t have any tone controls. 

Any thoughts? Thanks!
leemaze
But if the total is low, the components must be even lower (or theoretically at most equal).
Right, but atmasphere is stating that "a 7th harmonic at 0.005% is a much bigger sin in terms of coloration than a 2nd harmonic at 1%". So even a very low THD still begs the question, "at what harmonic"?
The Loki tone controls are really great.  Got the unit 5 days ago and used it to add just a touch warmth and boost the upper register.  It sounds really excellent - crystal clear, doesn't muddy anything at all.  I got matching AudioQuest ICs for the in and the out, and listening at night I no longer have burning desire to keep turning up the volume.

Worked like a charm - thanks for the idea @wolf_garcia @tketcham 
@chakster 
atmasphere  is too much of a gentleman to recommend his own amplifiers but those specifications are begging for a pair of M60s or an S30. I have altec 604Es with those exact specifications and they are sublime with a pair of M 60s 

leemaze,

Good to hear your Loki mini is working out. I moved my Loki mini to the main stereo system for a week just to see what it can do and when I put the Loki back into the smaller system it was a night and day improvement. Sometimes it takes an absence to really appreciate the difference. I think Schiit Audio is on to something.

-Tom