OK
I'll post a build sequence over the next few days.

Great!

I'm really sorry to hear that Philip.

Well what an unusual thread. One accurately answers a technical question and look at the calamity! If anyone can point out a factual error in my original reply I'd be interested to know. Anyone want to claim that zero feedback SET's are not in fact the worst for speaker control and flatness of response into a varying speaker load? A few measurements would soon show the facts.
The whole world of hi fi is getting beyond a sick joke when 100 years of scientific advancement in electronics, well documented in numerous textbooks and white papers etc, can be written off by some bod saying "yeah but me mates got a SET and it sounds tight in the bass to me so everything in science is bollocks".... and they are taken seriously!!
There are many things in this world that can be measured and put into order of best to worst in whatever context. Amplifiers are one of them. Now the measurements tell only part of the story of course. This is where our ears come in! BUT, in terms of saying things like which has the lowest distortion, the greatest grip on the speaker, the flattest frequency response into a range of loads etc, these are readily measurable and subject to the laws of physics. So readily measurable that the likes of Stereophile routinely does it.
There is no place for personal opinion etc in this. Facts is facts.
It's a good thing that medical research and space exploration seem rather more immune to Chinese whispers based on internet threads, something a bloke down the pub told me, what me mate Derek who is a bricklayer told me etc and rather more dependent on the knowledge and expertise of doctors and rocket scientists.
Due to the usual idiots being so predictable I'll repeat YET AGAIN that I am not a "all amps sound the same" or "measurements tell all" objectivist! Objective measurements and scientific rigour are the only way to get to a stage where an amp is designed and built and can then be listened to though! Obviously if the measurements say it has 5% THD and is only flat from 100Hz to 10KHz then it isn't hi fi and is a bad amplifier, whether it sounds "nice" to some people or not it patently is going to sound totally inaccurate and therefore falls at the first hurdle of the premise for High Fidelity! Back to the drawing board...
Since some seem to have trouble reading things I've said in the past, I'll point out that as someone who, apparently and allegedly is anti valve.... my latest product is a valve hybrid phono stage in which all the gain comes from the valves....
Anyone seriously interested can be considered for a try out of it (MC only). It has been described recently as similar-ish to the Aurorasound Vida... but better.

I heard a few valve amps mostly DIY I really liked Andrew Randall amp. It worked well with his speakers
These days I am a solid state guy (I used to have an all valve based system) and I can still enjoy a good valve based system. Today I was listening to a Temple Audio Prototype based on the Monos and the sound was as good as Martin system. A very different approach to music playback but stunning results

Perfectly calm old boy Just don't like having a lifetimes experience being misquoted/twisted by those of mischievous bent.... and certain agenda 

Even your own last comment appears to hint that there should be some particular amp that measures best and therefore Stereophile (and myself!?) should recommend only that... which is precisely what I'm NOT saying nor have I ever said.

Once an amp manages a minimum of say 0.1% THD, 15hz - 30KHz frequency response, damping factor of 16 etc, not a "high bar" to reach to say the least these days (and met or exceeded by various golden era valve amps from Leak and Radford to name but two), then an amp has sufficient technical competency for its measurable faults to have very little effect on the sound. It may then be judged on its subjective sound quality and subjectively tuned for best sound. This is basically my method.
If an amp can't meet even those fairly slack specs then its sound WILL be adversely affected by things that are readily measurable.
Some may like the sound of 5% THD and top end rounded off.... it gives that mellow old fashioned sound, syrupy, smooth as teflon coated velvet etc sound (from whatever technology) but it isn't hi fi so it isn't a good amp. It's a sound effects generator.
Seen those guitar amp modelling software plugins? They digitally recreate the distortion profile etc of old amps like a Vox AC30. The same could be done with a plugin to mimic the sound of a poor hi fi amp with 5% thd etc and in fact there are such plugins to try and replicate the sound of reel to reel tape recorders being taken slightly into the red.... These are part of the creative process when used in the generation of original music but have no part to play in its high quality reproduction.
Imagine playing a Mozart string quartet through a Vox AC30 emulator plugin...
My above comments apply to all amps no matter what technology they are based on of course!

I should add that I don't set out to achieve the most "accurate" rendition of what the engineer heard. As I have different ears and probably have varying tastes to the engineer, I'm just not interested. I simply want a sound that I enjoy. There is far more to sound than frequency response and I'm sure far more than we can ever hope to measure in its entirety.

A perfectly reasonable outlook on things.... but not hi fi...... High Fidelity is, strictly speaking, about the recreation of the original event, "the closest approach to the original sound" as Quad once said in their ads, not making it sound as you would prefer it to sound! Otherwise we may as well use graphic eq, "hall effect" or "jazz club effect" DSP as found on all in one midi systems! This then makes a mockery of all the effort that has gone in over many years of research by many people into making speakers low colouration, amps low distortion etc.
You may perhaps not like the way a real live violin sounds but whether or not you like it that is what it sounds like....
"There is far more to sound than frequency response and I'm sure far more than we can ever hope to measure in its entirety" Agreed. But I hope one day we can measure things which allude us now and so make even better hi fi's