Well,
The Jupiter Cu foil caps are steadily improving (25 hours at this point). The sound isn't "night and day" improved compared with the stock Solens cap, Israel Blume got excellent sound using this cap in the Frankenstein (undeniable truth). But! The Jupiter is an unquestionable step further up in music reproduction, the amplifier's strengths get deliciously better. I can't speak for other amplifier topologies but this Jupiter capacitor is fabulous in my 300b SET, utterly natural and it lets the music just flow and engage you (and I was already deeply pulled in before these caps were installed).
Snopro (Joe) I must thank you for mentioning this on your system page. What a nice addition they are for our amplifiers.
Charles,