A 1/4Watt would definitely suffice for input resistor for the cartridge.

The simple rule is that the total resitance if you connect a resistor R and 47k input resistance in parallel will be smaller than R. Since 47K is much larger than 100Ohm you may

a)replace 47K resistor with 100Ohms

b)Connect ~101Ohm resistor in-parallel with 47K Ohm resistor.

The general formula for your application goes from the following formula of the resistors connected in-parallel:

Rtotal = R1*R2/(R1+R2)

where Rtotal is the resistance you desire, R1 is 47K resistor and R2 is the actual resistor you need to match your experimented values

Rearranging the formula for R2 as follows:

R2 = [Rtotal(R1+R2)]/R1

Using these relationships you can build your own resistor bank that will step thorugh as many values as you desire until you find the best load resistance.

You may get a RadioShack project breadboard for such xperiment.

The simple rule is that the total resitance if you connect a resistor R and 47k input resistance in parallel will be smaller than R. Since 47K is much larger than 100Ohm you may

a)replace 47K resistor with 100Ohms

b)Connect ~101Ohm resistor in-parallel with 47K Ohm resistor.

The general formula for your application goes from the following formula of the resistors connected in-parallel:

Rtotal = R1*R2/(R1+R2)

where Rtotal is the resistance you desire, R1 is 47K resistor and R2 is the actual resistor you need to match your experimented values

Rearranging the formula for R2 as follows:

R2 = [Rtotal(R1+R2)]/R1

Using these relationships you can build your own resistor bank that will step thorugh as many values as you desire until you find the best load resistance.

You may get a RadioShack project breadboard for such xperiment.