I've been getting extremely good results by wiring a 10K pot as a cathode
 resistor. Put them in all your gain stages in the preamp, then set them
 initially to the default values. Then one by one, start turning the pots until 
you get the desired sound. You might want to put a 470 ohm in series
with the pot. 

Anyway, this may be "old hat" but what a great way to tune in your sound. 

After you got it where you want it, then replace with fixed resistors.

http://sounds.ampage.org/