> I am sure David Satz's ears are already perking up ...
No, actually your post was on line for well over an hour before my radar detected it.
Look, I can't (and don't want to) contradict anyone's listening experience. All I want to do is point out two things that are fundamental, well known, and (I hope) non-controversial.
[1] Impedance interactions between microphones and preamps can be complex, especially where transformers are present on either or both ends. The impedances of audio equipment with input or output transformers are specified as if they were purely resistive, but they're really not. So if you change the output impedance of a microphone, the audible result that you get with one preamp may not carry over (or not 100%) to other preamps, because different preamps have such different input circuits.
This is especially true if the input impedance of any cable+preamp combination that you use is less than about 10 times the output impedance of your microphone at any frequencies that occur in your testing. That is a recipe for "the sound of the microphone" to depend more on the details of that preamp's input impedance. If you have a preamp with adjustable input impedance, and you set it to its lowest-impedance setting (say, 600 or even 300 Ohms), you'll increase the likelihood of hearing some result of an impedance interaction. But would you really characterize a microphone on the basis of an "edge case" where you aren't operating it the way it was designed and specified to operate? That wouldn't make sense to me.
[Side note 1a] If a microphone's output impedance is high enough and the preamp's input impedance is low enough and/or the cable's capacitance is high enough, the output stages of some microphones that have output transformers can misbehave due to slew rate limiting. This can be audible at high levels and high frequencies, and the risk is greater when the output transformer is set to higher-impedance settings.
[Side note 1b] There are preamps--especially some that use input transformers with a large voltage step-up--that have audibly different high-frequency response depending on the impedance that's driving them. When that occurs, their impulse response is likewise affected.
[2] Whenever you strap the output stage of a microphone to a different impedance setting, you change its sensitivity (i.e. its output voltage as a function of the SPL). To compare one strapping versus another requires a preamp gain adjustment that is equal and opposite to the change in the microphone's sensitivity. Otherwise any listening comparison will be thrown off. Even experts may perceive small differences in level (that are too small to register consciously as such) as differences in sound quality.
In summary (ladies and gentlemen of the jury), the idea that you can restrap a microphone, plug it into a preamp, listen to the combination and say, "This microphone now sounds more ___ (or less ___) than it did before" just isn't realistic.
Again, I'm not disputing what anyone hears when I say that. But why characterize the microphone as sounding a certain way, if that perception depends on the relationship between its impedance AND the preamp AND the cable AND possibly the preamp's impedance setting? I mean, use any combination of anything that you like--but don't attribute what you hear to the wrong thing.
--best regards