I am working on my most recent 500-C and I got to thinking about coupling caps. I am pretty sure I am going to go the 220K resistor / .068uf capacitor combo route on this one. I usually use those yellow Illinois caps or Orange Drops for coupling, but got to thinking about fancy caps. I am curious to hear from those who have opted for fancy capacitors for coupling caps and the results they got. I am leaning towards using some Russian PIO caps off eBay, but am happy to hear other options. Please post links to places to buy them if mention a boutique cap. I found an older thread that was talking about Mundorf Supremes, but I couldn't find any for sale in the sizes referenced. I don't mind spending $20 per cap for the sake of trying this out. Also, if I go fancy for the output tube coupling caps, wouldn't I also want to use similar quality caps through the whole signal path? Finally, I have some super high end mil spec Micamold insulated PIO .1uf x 600V 1% caps that all test dead on .1uf. If I was to use these, what would be the ideal resistor value?