If you had a dozen pairs of classic vintage ubes in your closet

That's for sharing that lewm...   is that really true, my tubes are aging when I use them? when the heaters run?  Since "in many cases" why don't you find me some inexpensive tubes that outperform Siemens & Halske Cca 6922 grey plates circa 1962 or 1975 SSW 6N23P Reflectors.  I'll get out the soldering gun I've had for 40 years and ask it if I know how to use it, the iron I used 60 years ago is long gone.  The Heathkit multimeter I built 55 years ago finally gave up, who would think you could buy one for $14 bucks and have it delivered tomorrow. I don't agree with you on caps over tubes in my system and my wife does concur with my findings.  Perhaps you are biased in your listening, I'm not, very engineer based analytical. What works for you may not be for everyone. 

For all my tube equipment, I always purchase two identical sets of tubes.  One set is for every day use and one set is used as a reference.   Over a period of time audio neurosis sets in and I begin to doubt the tube’s performance/lifespan.  That is when in pull out my reference set and compare them to the everyday set.  If all is good, I merely put the old set back in and enjoy until Audio neurosis strikes again.  

I'm using those very same S&H tubes in my Manley Steelhead.  And this will killya:  They were given to me by a friend who converted to solid state.  Don't ask me if I like them, because I am biased to love them, now that you told me how much they could be worth.

You wrote, "Perhaps you are biased in your listening, I'm not, very engineer based analytical."  What about this exchange of ideas would support that idea? It's a scientific fact that we as humans harbor subconscious biases that affect what we see and hear, no matter how hard we may try to be neutral or "analytical". Spending big bucks on a tube would tend to enforce a very conscious bias in favor of that tube. This is why science that reports human behavior or relies upon it always has to include enough subjects to ameliorate the bias effect and preferably be conducted in a blinded or double-blinded fashion.  I am sure you know this, and that is all I was trying to say.  You could be analytical as a single observer, if you are making measurements with a reliable instrument.  But since this is all about opinions, there is no avoiding bias.

That’s all well founded lewm.... and I am making measurements with my reliable instrument, my ears..... which is what it is all about isn’t it? I had the wife listen to the S&H’s and some SSW 1975 Reflectors I have a small stock of and we agreed completely on what we heard. The S&H get the nod on vocals but the Reflectors simply play more music with greater detail, especially bottom end bass with stringed instruments such as bass fiddle.. Since I can't get any more S&H’s I ordered the last matched pair of 1975 SSW Reflectors my source had and a couple of 1977 Rockets as well. Should be well set now, at least until we finalize the digital cable from the streamer to the DAC.