Softest, smoothest sounding capacitors you've tried?

Some very nice caps come in lower voltages, so choice depends if they are going to be used in an active circuit, close to tubes or not, or speaker xovers.

Check the avialiable space.

Agree with Erik, and i would add MR’s, both excellent, other option is Jupiter HT beeswax, and at lower cost the Obbligato Gold premium.

rodman99999 is correct also about carbon composition resistors.

 

I have been Duelunds for a while especially their newTinned Copper Foil 

he best capacitors,  but they are Big,

just Jupiter Copper  foil are possibly a bit smoother but not as much detail .

Of course, nothing is cast in stone, but in general, you are describing paper & oil caps

 

 

V caps are very nice sounding caps. Quite expensive . 

Man what a loaded question! Power supply filter mundorf mundorf with PI CRC. Afe and vas really like kemet mkp wherever they fit. Vishay 18xx series mkp as well. Listening to my hafler 9500 with 100uf audio note /.1 uf mundorf mkp right before the output fets and man that combo is pretty special after about 40 hrs at high current... I know Solens don't get many accolades., but the mkps in my Dunlavy SM-1 x-overs I would never think to change. Flat neutral and oh so honest, so to answer the op, try Solen mkp. They may very well fit the bill.