I'm not an MSE, but I am a chemist & have had some materials science...and I've used liquid nitrogen (I'm guessing liquid N2 is the cryo liquid being used in the cryo 'treatments') more times than I can remember. Liquid N2 is a pretty generic, very inexpensive material with really nothing exotic about it.
There seems to be some confusion with regard to heat treating & simple submersion into a cryo fluid (N2). Heat treating and N2 submersion are two separate processes & shouldn't be blended into a single term (reference). i.e. a material can be heat treated without being cryo treated & something can be cryo treated with being heat treated. Neither process requires the other.
Material like metals & glass...have no 'molecules' to rearrange as they are not made up of molecules. They do have a crystal structure that can be impacted by heat. Metals can be thought of as elemental(iron, manganese, tin, copper...or alloys) protons in a sea of electrons or electrons in a sea of elemental protons...whichever way one wants to look at it. How these protons & electrons are arranged relative to one another determines the crystal structure (hold that thought for later).
Materials like plastics are made up of molecules & they too are impacted by heat. All these materials have a specific temp where they turn from a glass-like state into a 'malleable' state. With respect to polymers (plastics) this characteristic temperature is called the Tg (glass-transition temp). A polymer below it's Tg is basically a frozen solid...this can be at room temp or even much higher temps. Frozen is defined by the polymer molecules being unable to move or slide by each other. A plastic fork is a good example of a plastic(actually it's polystyrene) below it's Tg. When you heat this fork up to about 100 degrees C you notice that the fork can be bent. When you bend a hot plastic fork the molecules are sliding by each other & taking on a new relationship to one another(hold that thought for later). When you let the it cool the fork will be permanently bent. You'll also note that this bent plastic fork can be flexed when at room temp but when you let it go it will return to it's original, bent shape. 'Bending' a plastic fork stretches the polymer chains(the chains have a zig-zag conformation & thus can be extended...sort of like a coiled telephone cord stretching & recoiling)...when you stop bending the fork the polymer chains resume their previous position & the fork looks like it did before. Now dropping this fork into liquid N2 does nothing to change it's molecules relationship to one another...they are already 'frozen' into the fixed relationship they take on when their temp drops below the plastic's Tg. If you try to bend the cold, N2-frozen fork while it's still very cold the fork will no longer flex as it did before, rather, it will shatter as the polymer chains can no longer deform.
No doubt that heat treating has positive impacts on metals, and possibly other materials(plastics for one), but the reasons why are well understood, are far as I know. When you heat treat a sword (for example) the crystal structure changes(protons & electrons change their relationship to the protons & electrons that were close by before heat was applied). When you quickly quench the hot sword into water, oil...etc the crystal structure doesn't have time to change back to what it would be at room temp. The quenching has frozen a new crystal structure into place. This new crystal structure offers new properties...like hardness. Just like the plastic fork, cooling this sword from room temp to liquid N2 temps won't change the crystal structure...it's already frozen in place. When the sword returns to room temp it's properties will be the same.
Now if one just takes any material that exists a room temp, cools it down in liquid N2, and returns it to room temp I can't imagine any physical reason why the object would behave differently...electric or otherwise...and this comes from a reasonably good understanding of what the material "is", in an atomic or molecular sense. If cryo-treated audio accessories are actually being heat treated first & then dunked into N2 for a little exotic touch...then it might be more understandable that 'cryo treating' could change things(as the heat treating does). Although I'd guess heat treating & quenching a vacuum tube in N2 might be a little rough on the tube.
I've typed all this out to help folks appreciate the mechanics of why some might doubt the reported effects cyro treating. I have glossed over some of the specifics in how materials behave as explaining further could take much longer & be much more boring to some people. Naturally a good MSE could shoot some holes in what I've typed...but I'm not an MSE..I'm just an organic chemist with some appreciation & understanding of the materials that surround all of us.
Lastly, there may be reason why NASA, NASCAR... are doing cryo treating, but it's likely they know why. Just because they do it (if they do) there is no causal relationship that what they do, for the reasons they do it, will also result in audio system sounding better. If NASA...etc is actually heat treating with a very fast quench in N2(there would be reasons for doing this) & this is being called "cyro treating" ...well..."heat treating with a fast quench" might be closer to the mark.
Lastly, lastly, if we could cool our audio systems to liquid N2 temps & keep them there...then they would approach, or be, super conducting & THAT might sound interesting.
