The issues for amp to speaker are similar to what you are saying. The best transfer of power happens when the amp output impedance and speaker input impedance are the same. The real problems come when either impedance changes with frequency. But other places in (most) audio systems don’t need to transfer power. If you aren’t worried about power transfer you can simply use a low output impedance and high input impedance (or vice versa). Power transfer isn’t efficient but distortion caused by varying impedances is minimized.
In consumer audio the most common connection is high impedance inputs and low impedance outputs. Because the input impedance of a preamp (or amp, etc.) is high there’s virtually no current (V = I x R, where V is approx 2V and R is big). With little current there’s no real power issues (W = V x I, or W = V x V / R, With V being about 2V and R is, say 50000). (Output impedance - Wikipedia)
The impedance related issues center around an impedance that varies with frequency. With a constant impedance on the outputs and the inputs the only thing that happens is that the level of the signal is slightly lowered because there’s effectively a voltage divider formed: e.g. if the output impedance is 100 Ohms the input impedance is 10000 then the voltage level is lowered by (100 + 10000)/10000 or 1%. This doesn’t matter at all in the grand scheme of things, (Voltage divider - Wikipedia)
When the output impedance varies from 100 to 200 over the frequency band and the input impedance is, say a constant 10000, then the voltage level seen by the preamp varies from 1% to 2%, not very much but possibly noticeable.
The DS has a constant output impedance over frequency so there’s no problem if that impedance is 1 ohm or 100 ohms.