hey Roberto,

I've tried quite a few different capacitors for the passive mod, all rated at 47uF but with differing voltages;

Nicheon Muse FG 10v
Nicheon Muse ES 6.3v
Elna Skimic II 10v
Nicheon Muse KZ 25v
Nicheon Muse KZ 50v

I gave each one a couple of weeks "burn in" where I noticed that the sound changed over time till it finally settled down.

Best one for me was the Nicheon Muse KZ 50v, great all rounder but the kicker for me was it made music sound "alive", with it the music just seems to make a direct connection to your ears...and the good hifi stuff didnt matter.

Only thing with the KZ is that the metal legs are slightly thicker than the other caps, and have to be filed back a bit to fit in the socket holes on the Dac pcb.
5 minute job not a problem, and NO soldering involved!

A few of the other guys have tried different caps too, but its system dependant I suppose, so its worth trying different ones to see what suits you and your system.

I'm looking at Film capacitors, apparently a big step up from electrolytic ones.
The ClarityCaps ESA range is what Im looking at.

Maybe thats the "ultimate" capacitor for the passive mod?