This is my first poll. So if I screw it up, you'll know why. I've decided to upgrade my PPX3 Slam to an Extreme Platinum. I listen to Headphile modded K340's 95% of the time. Which output tubes should I get, 5998's or 6080's. More importantly, why? Thanks for your input into my buying decision. Rest assured that all input will be considered before making up my mind. Of course, I'll ask Mikhail too.