IC buffer and background noise

[denny99]

I'm using a General Guitar Gadget IC buffer pedal I assembled myself. The only modification I made was adding a 33K resistor from the negative tip of the output capacitor to the ground, to avoid DC leaking into the output signal.
I got myself a new true bypass distortion pedal to replace the buffered one I had (and also because I had to obey to a GAS attack  ) and I noticed an increased background noise when the pedal is engaged. As soon as I remove the buffer from the pedal chain, the background noise goes back to acceptable level.

Any idea? 
Thanks