Switchable Output Impedance
Switchable output impedance lets the user change the source impedance presented by a headphone amplifier's output.
Source impedance interacts with the headphone load. Changing it can alter level and, when headphone impedance varies with frequency, tonal balance. The feature describes an adjustable output property, not a headphone-impedance rating or guaranteed improvement.
Switchable Output Impedance — Headphone Amp
The control selects different source-impedance settings at the headphone output. These may allow comparison of how a headphone behaves with a low or higher source impedance. The numerical impedance at each setting is a separate specification, and its effect depends on the headphone used.
Compare the actual selectable values and the output to which they apply. A gain switch changes amplification rather than necessarily changing output impedance. Low, medium and high load-matching taps, or a separate high-impedance socket, do not by themselves establish this switchable-source-impedance feature. A fixed-output design should not be treated as adjustable because it supports several headphone loads.