Tubes vs Solid State - Imaging, Soundstaging, 3D

Well, all that matters usually comes out in the end. You just have to trust your ears. There is no equation or theory that can account for that 100%.

My view is there are many aspects of design that matter. I've yet to determine that any single one is always the determining factor. Most things are a matter of degree,not black and white. Only ones ears can determine how it all adds up.

If this were not the case, then all the smart engineers in the world would more or less be designing things pretty much all the same way. But obviously they do not. I suppose that's part of what makes this stuff interesting.

Cutting tech hairs perhaps, but I'm wondering what is the distinction between noise and distortion?

Wouldn't the harmonic artifacts introduced by NF be considered a form of distortion rather than noise?

I think of "hiss" as a form of noise. I think of harmonic anomalies as a form of distortion.

Both are obviously unwanted, but maybe worth clarifying to avoid confusion in the interest of talking apples and apples.

I did find this dewscription of the difference between noise and distortion.

It would seem to infer that noise is a "random" artifact.

Artifacts resulting from NF would not seem to be random, so I am wondering if that qualifies as noise and can be considered as a factor in a discussion regarding noise floor?

Back on the "life is too short" topic, see This

Paul and Yoko now buddy buddys. "Life is very short...." indeed!

Assuming the noise floor is low and can't be heard anyhow, what is there to hear below it?

Al's comments above are the correct answer to this.

Chaos Theory points to the 'why' of it- the amplifier with feedback is operating in a chaotic fashion where the noise-distortion floor is much higher with a constantly changing non-repetitive signal.

Csontos makes a good point in his post above. IMO this has more to do with feedback and less to do with whether its tube or transistor in theory. In practice though it is much easier to build a zero feedback circuit using tubes than it is with transistors. Ninety-nine and 44/100% of all transistor amps run a considerable amount of feedback, hence the generalization.

For the time being designers have yet to universally recognize the importance of human hearing rules in audio design, so we are likely to see considerable differences in opinion for quite some time :)

In this conversation I've not discussed preamps although I have alluded to them by using the word 'circuit' as opposed to 'amplifier'. The same rules of human hearing of course apply to preamps, and you do deal with the same issues of feedback. However in preamps it is very easy to build a zero feedback circuit with vanishingly low distortion and wide bandwidth, so the argument in favor of feedback weakens considerably, especially in the face of the damage it can do (if you want to build the preamp with opamps though you are kind of stuck- that can only be done with feedback). If the preamp looses information, it really does not matter how good the amp or speakers are- you can't recover lost information downstream.