No preamp has an output impedance of 100K ohms. Just ain't so. You need to know the output impedance of your preamp. Now it's possible that the input impedance of your preamp is 100K ohms. Impedance should not be matched. The general rule of thumb is that the input impedance of the driven component (amp in your case) should be a MINIMUM of twenty times the output impedance of the driving component (preamp in your case) so, if the input impedance of the amp is 50K ohms the general rule of thumb is that the preamp should have an output impedance less than 2.5K ohms, which just about all of them do.
There are certain current mode preamps and amps, such as Krell and Roland, I believe, that used matched impedances in certain circumstances, but this is a different topology altogether.
There are certain current mode preamps and amps, such as Krell and Roland, I believe, that used matched impedances in certain circumstances, but this is a different topology altogether.
