Full detailed sound at 30 - 40 - 50 dB

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 

But if the total is low, the components must be even lower (or theoretically at most equal).

@willemj  When you have really low numbers typical of traditional solid state amps, the problem is that the higher ordered harmonics are simply not as low as they should be, while the lower harmonics are indeed suppressed. It cannot be denied that this is a coloration!

This results in the amp being brighter and harsher than real life, even though on the bench the amp measures perfectly flat. Our ears are very sensitive to this distortion spectra, and we've known this for the last 80 years(!) or so (see Radiotron Designer's Handbook, 3rd edition).

I suppose I should not be amazed that basic physiological information about how we hear is ignored on an ongoing basis if the last 8 decades are any indication.

But if the total is low, the components must be even lower (or theoretically at most equal).

@willemj The problem is that the ear does not treat all harmonics on equal ground. It is far more sensitive to the higher orders! Think log scale...

We've known this for the last 80 years (see Radiotron Designer's Handbook, 3rd edition) and I suppose I should not be surprised that such knowledge continues to be ignored.

Although traditional solid state amps do have overall lower distortion, the distortion that they **do** have is the higher orders, and higher than you see in most tube amps, hence 'brightness' and 'harshness' attributed to them. If you are not aware of this already, the ear converts all forms of distortion into tonality.

The other complication is Fletcher-Munson, the fact that our ears are tuned to birdsong frequencies (especially at low volume levels) which makes it all that much easier to hear the distortion of solid state amps at low volume levels.