I absolutely guarantee your fellow engineers will write it as KHz. I just did a quick scan of emails from my engineers and I can find many instances of it. It is probably why I do it. Most of these are MSEE and some PhD. I am working on engineers from 3 continents and who knows how many different backgrounds.
w.r.t speaker wires feeding back into the amplifier, or a bridge or phono catridge, you keep saying loop. If there is a ground connection. it is not a loop. This is the mistake you keep making. It is not a loop. It is not about the induced currents being different. It is about where they go once the meet the single ended piece of equipment, i.e. the amplifier, the phono-amp, the bridge amp (which would never be single ended). At the amplifier the resistance, I guess ideally impedance, must be the same so that the induced voltages are the same, or they do not cancel. If you have a ground connection, or simply a difference in termination, as any single ended piece of equipment will be, then you will have an induced voltage difference from common mode injected currents.
Let’s go back to our speaker connection. I have common mode current that goes towards the speaker. Both see the same impedance at the speaker (it is a floating speaker after all). The voltage on both sides of the speaker, for argument/illustration raises the same amount, hence no change in voltage across the speaker. If the current goes the other way, one side sees the impedance of the amplifier. The other (ground) sees the the impedance of the amplifier, but also sees a parasitic path through through that ground and out to "somewhere". Now you have a differential voltage caused by the common mode noise.
This is common mode. There is still the superior symmetric coaxial structure for rejecting the generation of differential currents from electrostatic fields and even for magnetic fields, the coaxial structure provides rejection.
Let’s approach this from an engineering perspective. My search, though limited, resulted in a consensus that for single ended connections, which we are talking, and which you cannot hand wave away a ground connection that is a resistance/impedance significant with respect to the termination resistance/impedance, that coaxial cables are superior for rejecting external EMI. If I am wrong, and what you say is true, there should be ample evidence of this on the web one would prefer with measurements. Here are some measurements done by an engineer who posts on ASR (not Amir/a mod). I also have another posts from a cable company where they talk about most RCA connections being fully grounded (I know I saw that in the past when playing around with tube equipment). That throws out that big resistor to ground in all cases argument and makes the case strongly for my system dependent argument.