What effect does current have on the input of the amp?

[John Kolbeck]

So a typical electric guitar puts out about 150mV, and perhaps 0.01mA. What effect, if any, does it have on the pre-amp of an amp if the guitar supplies more or less amperage, for a given voltage?

[g1]

For any fixed voltage level (and frequency), the amp input impedance will not change, so the current will be essentially fixed.
For the current to increase or decrease, so must the voltage.
I'm not sure I understand the question.

[John Kolbeck]

I think that answers my question, actually. Thanks a lot.

[nickb]

The current that flows is a consequence of the voltage. The voltage is like a force that drives the electrons through the various impedances of the pickup, the guitar pots and the amp inputs.

Since the pickup voltage is not going to change you can only get more current if you lower the total impedance and that means the amp input in practice.

If you model the pickup as a voltage source Vp in series with an impedance Zp and the amp input impedance is Zi then the voltage at the amp input is

Vi = Vp x Zi/(Zi+Zp)

The point is if you lower the amp input impedance you get less volts so the pickup signal is attenuated. For that reason in contemporary audio designers aim for a high amp input impedance to maximize the voltage.