I don't want to beat a dead horse but I'm bugged.

Of course if you substitute the term reliability in place of measurement, that’s a fundamentally  different argument. Without question I would choose high reliability compared to low reliability. But that wasn’t the point of this topic thread. Tube audio components are notorious for yielding poorer measurements as opposed to transistor audio components. 
 

Yet well made tube components are wildly recognized for their Very long lifespan/years of service with reliability. This is accomplished with their relatively comparative poorer measurements. So even here there is no correlation with test bench measurement and reliability/longevity as it regards tube equipment.

In the example above you would choose product A over product B. That’s fine. My point is those measurement do not ensure superior sound quality nor reliability. So I’m trying to determine where/what is the intrinsic advantage of bestowed by the better measurement numbers.

Charles

Tube parameters change significantly over their life. Put in a new tube it sounds like a different amplifier. It’s not the reliability that I had issue with, it was that I never knew whether my amp was operating at its best.

I enjoyed it at the time. Pick what works for you.

Superior sound is subjective. What you like someone else may hate. Many roads to the same place.

Sound.

You hear sound not graphs and measurements.

Sound, music.

You are right if you speak about the differences in gear....

But sound subjective evaluation is not only pure relative taste, it is also a LEARNED HEARING experimental journey with acoustic and psycho-acoustic experience and principles...

Difference in gear design and specs are also SUBJECTIVE and are judged by our own needs and expectations...

Difference in room acoustic are no more only subjective, you can objectively CONTROL a system/room at will and you can learn from this OBJECTIVE experiments installation the more you explore it...

That is my point...

Differences between relatively basic good gear at any price will not replace the HUGE impact of small room acoustic and psycho-acoustic control done right...

We learn to listen... Our tastes are secondary like our gear pieces are secondary if they are well chosen gear to begin with and in accordance with our wallet...acoustic is primary for our understanding of sound...

Saying the opposite is pushing people in the marketing trap of obsessive upgrading and entertain a universal ignorance about how good sound experience emerge in a specific room for our particular ears...

Also keep in mind that there exist a minimal threshold for  what may be  experienced as a good sound experience related to the S.Q./price ratio for the gear you own...One this treshold is reached and master upgrade are way less attractive...An improvement is ALWAYSpossible for sure but here the ratio S.Q./ price plays for most of us...

Acoustic cues and factors  that may be and must be controlled : timbre, bass, dynamics, imaging, soundstage, LEV/ASW ratio, etc all these acoustical cues and factors  will give us an OBJECTIVE number of "tags" and indexes all along the subjective road...

Controlled Correlation between our subjectivity and objective installation is the heart of acoustic and psycho-acoustic learning experience and experiments...

Superior sound is subjective. What you like someone else may hate. Many roads to the same place.