I built the serendipity a couple of years ago and never really liked it compared to some of my other builds so it just sat there unboxed. I thought I would try a few mods to see if I could get a better sound out of it. Tried a JRC 4580D and Bat 41 and oh my this this sounds wonderful! Has a really nice softness about the tone that I really dig.
Also realised that having my Boss TU2 tuner fist in the chain was not such a great idea. The buffer in that bad boy was really messing with the tone of my Sunking and Arisocrat - put the Tu2 after all the drives in my chain and every pedal sounds better!
Dang it now I have to box the serendipity up now sounds too good to leave it on my desk!
I like it a lot better with the JRC4558D in there than the AD712. The AD712 sounds too sterile to my ears. I'll have to check out the 4580.
-Aaron
jrc 4580D is what wampler uses in his Ecstasy/Euphoria/zendrive /dumble pedal