Input impedance resistor, F4 amplifier

Is the quality of this input impedance resistor that important for the quality of sound? I am asking this question because I need to bring the input impedance fron 47500 ohms to around 41,000 so i can use a given cap in my HP line filter. I am considering installing a 300,000 ohm resistor from line to ground in the preamp's output which would give, with the F4's impedance an
effective impedance of 41,000 ohms. So, I only have Xicon metal films for this and was wondeing if this choice would affect the sound quality.
Thank you all.
 
F4 doesn't know what is feeding it with signal ;

little Jfets doesn't know what value of resistor is from their gates to gnd

what you need to think is proper value of net needed to linearize xformer ( net means either solo resistor or resistor in series with cap , across secondary )

so - just leave F4 as is , thinking only of needed voltage to feed it .

also - think about using xformer in autoformer mode - that way you'll have slightly improved sound