Jerrold, your posts in this thread are golden, and come closest to explaining (I think) what the appeal of playing through some tube amps has for me and probably many others. It seems like these aspects of the amps' performance are being taken into account more now when designing amps and pedals designed to emulate the feel and tonalities of various classic tube amps.
In practical terms, it's it's probably why so many tubeheads like the VT pedal, the Streamliner, and the Mesa Walkabout, and why some all tube Mesa amps aren't very popular, because they sound too 'solid state'!
I'm glad Seamonkey made that point about vinyl for two reasons. One is that people can tell the source is vinyl even if reproduced digitally, and the other is that people may prefer tubes and vinyl for the artifacts and distortion they produce.
100% fidelity in amplification of an instrument's or an audio source is of ZERO importance to me, and obviously to many others. We seek a pleasant listening experience, and that may be because certain types of distortion, etc, are inherently pleasing to us as humans, and also obviously because we prefer what we are used to hearing.
By focusing on the hiss and pops, he is missing the point that maybe much subtler distortion is present that knocks the harsh edges off the highs, that seems to separate instruments more, or make voices appear more like when someone is singing in a room rather than through a sound system, etc, etc.
And of course when we are talking about amplifying instruments, fidelity is only important to a point, because we are generating sound rather than reproducing it. Everyone has their own idea about how much 'fidelity' they want from their rig, because nobody really knows what their instrument actually sounds like, though we talk as if it's a given. Since no one has heard their own electric bass loud enough acoustically, we all to an extent like a certain amount of colour, i.e. distortion, EQ, etc.
Some of us have heard our instruments through very flat rigs, and want that, some want masses of colouration and baked in EQ, and some varying amounts in between, but when you think of it, electric instruments are designed more often as not as part of a system that includes the characteristics of amplification traditionally used, and recording techniques and their various methods of storage and reproduction.
Excuse my rambling here, lack of intellectual rigour, and not addressing the actual topic, but I think they are relevant when discussing testing, as they affect what is tested and to what purpose those tests are used for, how they are framed and what they intend to reveal.
. 
