At audio frequencies, characteristic impedance is almost always irrelevant. hi-Z is a crystal mic, guitar pickup or crystal phono pickup source.lo-Z is a dynam

At audio frequencies, characteristic impedance is almost always irrelevant. hi-Z is a crystal mic, guitar pickup or crystal phono pickup source.lo-Z is a dynamic or condenser mic source. Obviously, a preamp may be used as an impedance converter to lower hi-Z to loZ. There's such a preamp in the condenser mic. The cables are hiZ or loZ only in that they're generally used with one source or the other. But that's by convention. loZ is usually a balanced XLR connection; hiZ is generally an unbalanced 1/4" connection. hiZ is generally at around 1 megohm. loZ is archetypally 600 ohm. Line is neither; it's 10,000 to 50 or 100k ohm.