I had gotten to the point of soldering this pedal together and testing some sketches, and it worked great, except for the loud hiss coming from my amp every time I would stop playing. As a result, the pedal sat, unfinished, on a shelf for a large part of the last year. A friend of mine, who has been playing with electonics for the last year has recently found a great hardware solution to this problem. Placing a 100uf inductor on the two ground pins of the output jack eliminated this noise completely! Looking back to last night, I wish we would have taken some pics of the oscilloscope, but instead, we immediately began toasting and that was all she wrote.. The major difference is that I did not use the recommended jacks when wiring this together because I wanted to put this in a metal enclosure.. I tend to be rough on my things.. I am not sure if this will matter when it comes to your individual project, but hopefully it works, or will at least provide a good jumping off point. I have no idea why this worked btw, and neither did my friend.. Just tinkering until a solution appeared. Anyways, heres a couple pics that shows where its located. Good luck!
I also tried tge inductor solution with no progress.
I think that RedLlama saw some improvement in the noise because he was using external jacks and pots. He posibly had some ground loop that the inductor was able to break.
In my opinion the inductor does not improve the design.