Output impedance (Z) in isolation doesn't give the full picture.
When two devices are chained, like in an audio rig, the source has an output impedance and the destination has in input impedance.
In theory, for max transfer of power, Z(out) should be 0 and Z(in) should be infinity.
In real world, Z(out) should be low and Z(in) should be high; like order/s of magnitude high.
An acceptable ratio when using chains of SS equipment is Z(in)/Z(out) = 10
Eg.
CD player Z(out) = 76 ohm
Preamp section Z(in) = 20 Kohm
Z(in)/Z(out) = 260 (much higher than 10)
This chaining will have very less power loss during transfer of signal.
If the ratio is very low, the source will start seeing the destination as a load and it may affect gain/volume/performance.
This matching was important in tube systems due to output coupled components like transformers, etc.
In the SS world today, one doesn't need to worry about this. The ratio is most of the time orders of magnitude.
Cheers,
Raghu