http://en.wikipedia.org/wiki/Impedance_matchingImpedance matching is the electronics design practice of setting the input impedance (ZL) of an electrical load equal to the fixed output impedance (ZS) of the signal source to which it is ultimately connected, usually in order to maximize the power transfer and minimize reflections from the load. This only applies when both are linear devices.
The concept of impedance matching was originally developed for electrical power, but can be applied to any other field where a form of energy (not just electrical) is transferred between a source and a load.
Matching is obtained when ZL = ZS*.
(http://upload.wikimedia.org/wikipedia/commons/8/88/Source_and_load_circuit_Z.png)
Terminology
Sometimes the term "impedance matching" is used loosely to mean "choosing impedances that work well together" instead of "making two impedances complex conjugate". The looser interpretation includes impedance bridging, where the load impedance is much larger than the source impedance. Bridging connections are used to maximize the voltage transfer, not the power transfer.
With modern audio electronics, impedance matching degrades audio performance;[1][2] impedance bridging is used instead.
hmm... maybe we want impedance bridging instead... this is a voltage process, and it is in the "audio range" as stan says in the NZ video
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