I am really not impressed with the Sovtek tubes that are currently in my YBA200. I havedecided to got with JJ 12ax7 and 12at7 (as was recommneded in a previous post to reduce the gain. I think a 12ay7 would be a bit too clean for my taste) in the pre amp. I am debating between a few options for the power amp section. SED 6550C SED SVKT88 EH 6550 EH KT88 (for the same price as the EH6550 at dubedepot.com) JJ/Tesla KT88 JJ/Tesla 7027A (i'm not sure if this is even possible to use in the YBA200) Any opinions or experience with these tubes would be great.