This is also Borbely Erno Design Jfet Buffer and I use this to make my pre-amp. I use two low noise regulator and 4 buffer module to become a full balance pre-amp. The sound is very good and distortion is also very low. I have tried to use a transistor second stage but the sound become aggressive and harsh. Thus all Jfet is my choice!
Jfet regulator Circuit *updated on Dec 23, 2009*
Jfet Buffer PCB Errors *updated on Jan 15, 2010*
FFT jfet buffer xlr log at 10V
Update on Oct 20: After redo a bit on the wiring of power supply and put a NTC from star ground to the casing, the distortion has improved to below 0.0001% at 10Vrms output balance mode. Distortion is also very low at 0.0026% at 1Vrms output. The good thing about this pre-amp is that the higher the output level, the lower distortion it will be.
Some FFT measurement after improvement: