The Sylvania 3 mica black plates have become famous (I think mostly due to Joe's write-up on AA) and they pretty much live up to the hype in my Jolida JD100 cdp. However, I almost prefer the GE black plates - depends on my mood. Both are excellent replacements for 12AX7s. They have convinced me to get more tube equipment! The GEs are a little more accurate than the Syls and seem to have a tighter bottom end. The soundstage has fantastic 3D imaging compared with new Sovtek and EH 12AX7s.
