I have both the Svetlana 6550, and the kt88. In my system the 6550 has better bass, but the kt88 absolutely kicks but in the midrange. Of all the kt88's ( new tubes, not nos ) The Svetlana has the smoothest mids and highs. I have also had discussions with Leonard @ ARC. I think as far as he is concerned the only output tube that exists is the 6550. Oddly enough though they do sell kt88's on their website, for an ungodly price I might add. I would also recommend that you have the kt88's properly biased by an experienced tech.
Having said all that ( and reading the other posts ) the sound you get will depend on the rest of your system, and room. I've got a pair of Chinese kt88's that sounded lifeless in 1 system, but when I put them in my second system they sound great!
BTW, if your interested ( or anyone else reading this ) I have 2 matched quads of Svetlana kt88's Basicly new ) I'll sell you for .50 on the dollar.
Having said all that ( and reading the other posts ) the sound you get will depend on the rest of your system, and room. I've got a pair of Chinese kt88's that sounded lifeless in 1 system, but when I put them in my second system they sound great!
BTW, if your interested ( or anyone else reading this ) I have 2 matched quads of Svetlana kt88's Basicly new ) I'll sell you for .50 on the dollar.