I have good luck with Allied. Julia is very helpfull. That cap is the output coupling cap; is that correct? If so would it be possible you might walk us through the Ohm's law math required to find that value? I understand if it is too much but I am attempting to access the Radiotron theory and struggling due to lack of math skills. I also happen to have the NEETS program I ordered a while ago. Anything pertinent in there. I see you have used it twice now. Thanks Douglas. We are very hyped about the 807 amp project to pair with the pre. I have traded my EAR el 859 in order to do PP and this is right up the alley.