Have you seen any CABLE measurement tests?

For RLC measurements, see Audioholics, esp. the cable faceoffs listed on this page:

http://www.audioholics.com/techtips/audioprinciples/index.php

"Straight wire without gain" is an ideal, not a real-world phenomenon. All wire will have some tiny effect on frequency response, most commonly a little roll-off in the top octave. And when I say a little, I mean generally well below what humans can detect. There are exceptions, and it's certainly possible to intentionally make a cable with really bad FR. But for most speaker-amp combinations, any cable with reasonably low resistance (meaning reasonably thick) will provide audibly flat frequency response.

Which is why cable purveyors don't publish FR plots--because they'd show something the purveyors don't want you to know.

measurements do not necessarily correlate to observed sound

Depends what you mean by "observed sound." Our everyday observations of sound are heavily influenced by non-sonic factors--setting, mood, prior opinions about the performers/equipment, etc. Your brain is wired to synthesize information from all your senses, plus stored memories, and that's what it does. Obviously, measurements of sound aren't going to tell you anything about all the non-sonic things that are part of your mental mix when you're listening to something.

But if we isolate our hearing perception from all that non-sonic stuff--by listening without knowing what we're listening to--there is a high degree of correlation between certain measurements and our perceptions. See, for example, the work that Floyd Toole and Sean Olive have done on speaker preferences. A good basic summary is contained here:

http://www.harman.com/about_harman/technology_leadership.aspx

See also Earl Geddes's work in progress here:

http://www.gedlee.com/

are you saying a person listening blind will usually prefer a cable which measures better than another cable ?

No, I'm saying that a person listening blind will usually not prefer either, because he usually won't be able to tell them apart. When he can tell them apart blind, the measured differences will be substantial, because you need a substantial difference in RLC values to produce an audible difference in frequency response.

IOW, for cables what we can predict from measurements is whether differences will be audible--again, assuming you don't know which is which. If you do know which is which, that knowledge alters your perception.

finally what about the particular components feeding and receiving a signal, isn't there an affect of the components being interfaced upon a cables performance ?

Yeah, but again this is no mystery. If you know the output impedance of the amp, the RLC of the cable, and the impedance curve of the speaker, you (or rather, some software) can plot the FR curve of the cable in that system. In general, the output impedances of solid state amps and the impedance curves of most box speakers are such that most normal cables will not produce audible FR differences. (They may produce level differences because of resistance losses, which is why level-matching is required for good tests.) If you're trying to drive electrostatics with a tube amp, YMMV.

Twl: You're obviously not any kind of scientist. If you were, you'd know that there are no irrefutable facts, and whole theories are never proven by single experiments. (Remember what Einstein said about that.)

That said, just which conclusion are you talking about?