Timothy Lawler said:
Question for mshilarious: what makes/models of pre's would be classified as having low impedance inputs?
That's a good question, I haven't taken a tally, but modern preamps are nearly always 1K ohms or higher, or they have adjustable input impedance. Changing the input impedance is a feature that is mostly useful for dynamic mics; the interaction of the dynamic coil, transformer, and input impedance gives some interesting tonal options.
Generally, lowering the preamp's input impedance with a (transformerless) condenser mic will simply tend to lose sensitivity without much effect on tone. Therefore you'll see lots of condenser mics state in their specs that preamps with input impedance over 1K ohms are recommended.
So I would expect that we would mostly find that vintage gear has low input impedance, going back to the old impedance-matching days where everything was 600 ohms, input and output. That maximizes power transfer, but it's not that useful of an idea when we are concerned only with the signal itself (voltage), and not its ability to do any work.
There is another benefit to low output impedance, that has to do with driving long cables. The resistance of the cable is still a relatively trivial matter, but capacitance can grow to a problematic level with a high output impedance. The output impedance of the mic and capacitance of the cable will form an RC filter, which is a lowpass filter. This is why guitarists avoid using long cables; it's not as bad with a high output impedance mic, but were one to run an MSH-1 (Tape Op mic, etc.) through a 20ft cable to a 100ft snake, that is starting to get into the audio range and causes an attenuation of high frequencies.
