Resistor in phono stage

The ARC PH3SE in a MM only phono stage.  It has a factory set fixed output of 54db gain, 47Kohm impedance and 90pF of capacitance.

You can change only the capacitance by soldering in different values of resistors.  I would make sure if this has even been done.  I have owned several of the PH3 and PH3SE units and none of them had ever had a resistor soldered in.

Here is an excellent white paper on loading:

http://www.hagtech.com/loading.html

Page 2 of the PH3 owner's manual talks about changing Input Impedance and Input Capacitance:

http://www.audioresearch.com/ContentsFiles/PH3%20manual.pdf