In the old days before integrated circuits, one could change the impedance of a receiver's auxiliary inputs by changing the resistors nearest the input plug in order to match that input volume to the radio or other input devices. Typically, there was a resistor in series and another in parallel. I did it once to increase volume of an input by reducing the in-series resistor. I could see then, but have not looked inside a modern receiver to know if the pair of resistors are still used at the input plugs.
- Gil Laster Charlotte, NC [Non-text portions of this message have been removed]
