which Jensen cap to use?

http://www.humblehomemadehifi.com/Cap.html is a great site for capacitors

Be forewarned that nearly all paper and oil caps can exhibit electrical leakage (i.e. they don't always block 100% of the DC voltage) which can skew the bias voltage of succeeding stages of amplification.

They can do this out of the box or after a few years of operation.

Atmasphere is right--and sometimes the result can be disaster for the circuit. But, of course, the sound you describe "warm with lots of details" is (best/only?) achieved with copper pio caps.

Can't compare the three varieties you list, but I have used the copper Jensen pio in a SET amp for years. The sound is just as you describe, and the caps have proved trouble-free.

Wasn't the leakage problem fixed some time ago? BAT continues to use Jensen caps....

Wasn't the leakage problem fixed some time ago? BAT continues to use Jensen caps....

- No, Mr. Khomenko uses caps made by Jensen according to his own specifications