Full detailed sound at 30 - 40 - 50 dB

If you are wanting full detail at lower volumes, this is an area where tubes rule. This is because they tend to have a lot lower distortion at lower power levels. Something to think about...

Hi @atmasphere 

Given your statement, at what decibel level do you consider the volume to be something "higher" than lower volume? The essence of the question is at what power level do tubes no longer "rule" over SS because of power concerns. Thank you. 

Tubes rule! Or not, but I didn’t know tubes were better for low volume (I learn something from Atmasphere about once every 4 and a half days), but I prefer tube amps anyway so I don’t recall the difference since I’ve had a tube amp in the rig for so long…I have noticed better low level sound since I put a pair of efficient horn speakers in the rig, but the tone issues with lower levels are always there so you’re going to need loudness compensation for that anyway if you want the highs (and lows) to get to your earballs…hense my Schiit Loki usefulness. One thing about the Loki is it’s single ended RCA only so balanced "pre to amp" users have to run it through a tape loop or something (although not all preamps have those these days). Maybe the Schiit-heads next EQ (Loki Maxi?) will be balanced. Also the immediate slam and general snappy response of a great tube amp (mine is a lowish powered Dennis Had Fire Bottle HO), along with the inherent tonal "rightness" (an official audiophile term), makes tubes at least "seem" balsier than most SS amps at higher volume when paired with appropriate speakers.

For sure tubes are FAR better at low level resolution than any SS .
 Only you know what loud is to you .Atmasphere is the THE tube expert on
here but from the maybe 6 tube amps and 30 SS amps I've owned I would say a tube amp with GOOD transformers putting out 30 watts is at least equal to a 100 watt SS .

Maybe the Schiit-heads next EQ (Loki Maxi?) will be balanced.

Exactly!

I mentioned that here: https://forum.audiogon.com/discussions/schiit-reference-sytem-review-freya-into-yggdrasil-into-vidar... 

Given your statement, at what decibel level do you consider the volume to be something "higher" than lower volume? The essence of the question is at what power level do tubes no longer "rule" over SS because of power concerns. Thank you.

Its not so much a decibel thing as it is a distortion thing.

Take a look at the distortion curves of a typical solid state amp. At a certain lower power level, the distortion is at its minimum and as you go to lower levels the distortion can be significantly higher! This is not a given with tube amps, even push-pull amps (our amps are push-pull but distortion linearly decreases to unmeasurable as power is decreased).

So that power level is about 5-7% of full power with most solid state amps. If you've ever heard that bit about the 'first watt' being the most important, that's because its all about distortion (or in this case, the lack of it). BTW, Nelson Pass has a set of solid state amps called the 'First Watt' amps and they are so-named because they diverge from the usual solid state amps in that they too are very low distortion at low power levels. Their designs are also quite minimalist (even simpler than and not unlike tube amps in that regard) although they don't make a lot of power.

If you want good resolution so you hear everything (including good bass) at lower levels, this is what you have to do: tubes or a low powered solid state amp like a First Watt.

Now to the latter portion of the question- even at high power levels, the presentation continues to be all about distortion (or the lack of it). The thing is, the ear weights certain forms of distortion over other forms. What I mean by this is most people understand that the ear hears sound pressure on a logarithmic curve. What is considerably less understood is that the ear also detects harmonics on something that looks like a log curve. It is far more sensitive to higher orders (in particular the odd orders) than it is to the lower orders like the 2nd or 3rd harmonic. For this reason, we tolerate large amounts of lower ordered harmonic easily, but don't tolerate higher ordered harmonics well at all.

Audiophiles have terms for trace amounts of higher ordered harmonics; 'bright' and 'harsh' are common examples. This continues to be the big difference between tubes and solid state with regards to distortion! Now think about that weighting issue I mentioned: essentially, solid state amps have much **greater** amounts of distortion if you weight the distortion according to how the ear/brain system responds to it (all forms of distortion are converted to a tonality of some sort BTW). So a 7th harmonic at 0.005% is a much bigger sin in terms of coloration than a 2nd harmonic at 1%. Its a bit of an inconvenient truth.

Our measurement and testing regime is a good 40-50 years behind our understanding of physiology at this point, which is why there is still a tubes/transistors debate going on in high end audio.