I decided to make a test jig which just plugs in instead of the active audio board, I did it like this mainly as temporary to allow easy and quick swapping of the caps, it also goes through the onboard relay same as the active board

I also refitted the stock tans etc around the dac until I can get the smaller Silmic II's. the ones I fitted was a little big

The passive mod will have varying results depending on your kit mainly what the dac see's on the output, things like capacitive loads , long interconnects etc may influence things more than with the active audioboard Watch out for things like distortion or clipping.

The blue caps in the pic are Epcos polyester , the polypropylenes I tried first are just huge
I'm going to have a scrounge to see what others I have, the sound so far is smoother, less forward . Bass seems deeper