No, because you offer no context - there's no such thing as an "ordinary audio amplifier" - post the circuit you're refering to and we can discuss that.
On an operational amplifier the input impedance will change with the set gain. A unity gain operational amplifier gives a near infinite input impedance.
Raise the feedback resistor to obtain some gain and input impedance decreases.
On other types of amplifiers, it may not be the case.
Miguel
On an operational amplifier the input impedance will change with the set gain. A unity gain operational amplifier gives a near infinite input impedance.
Raise the feedback resistor to obtain some gain and input impedance decreases.
On other types of amplifiers, it may not be the case.
Miguel
I suggest you try reading your opamp theory again, input impedance is set by the input resistor on both inverting and non-inverting amplifiers - nothing to do with gain.
I'm going on sea and i don't know if i can safety connect my IPOD nano to external computer speakers like this one https://www.maincomp.com/uploads/CB-80401.gif which has amplifier integrated.
The output of the ipod will probably drive the computer speakers perfectly.
But the computer speakers are small and will not have any bass nor much power.
There is nothing that is unsafe. The ipod has a low output impedance that has mA of current and the computer speakers have an amplifier with a high input impedance that draws only uA of current.
But check the input sensitivity of the computer speakers to see if the output level from the ipod is high enough.
The input sensitivity of your hi-fi amplifier is an input of 150mV RMS for full output when its volume control is maximum. Its input impedance is 47k ohms.
Your ipod probably has an output of at least 250mV RMS so it will drive your amplifier to full output on loud music peaks with the volume control turned down a little.
The computer speakers also probably have the same input sensitivity.
higher sensitivites mean lower levels of input signal the voltage levels and power are most often rms values, higher sensitivies mean that the amp can be driven from sources with lower level
OK, I found another explanation, is it correct?
I don't understand what is bold. If amp have higher sensitivies (input signal can be higher consequently input level can be higher no lower ? )