I agree with corndog - get a couple of Miflex copper foil capacitor, value of .01uF and use it as a bypass on your sonicaps. Do you have foil inductors? If not, that might be a good upgrade too. And last but not least, the resistors can be changed out for the fully copper based Path Audio resistors.
The Miflex bypass caps will have the biggest affect on the sound, followed by the inductors and then the resistors.