Which 6SN7's for Rogue 99 Pre

The switch was probably because the supply of new Philips tubes dried up. They were military tubes from the 1980's.

Blue Circle was using them also in the BC21 preamp and BC2 mono blocks.

I got Electro Harmonix with my Rogue99 Magnum. I used them side by side with some Sylvania chrome domes Mark obrian sold me and they sounded fine. I'm running Crome domes side by side now and its great. Thinking about trying some Ken Rads or Raytheon VT-231's next. Anyone wanna comment on that?

I tried the Electro Harmonix ( bought from Upscale) in my 99 Magnum and they were micro phonic as hell. Nothing I tried would quiet them down. I bought new ones from Mark o Brien and they are fine. I honestly dont remember what brand they are though...

Pretty hard to beat either your Sylvania VT231's or the Kenrad's mentioned by sugarbrie. If you feel like experimenting a bit, you might want to try some 5692 tubes, which are in the 6SN7 family tree. I have used them with very good results, I personally believe that they produce a more cohesive overall musical experience than the VT231.

Sugarbrie mentioned the Sylvania 6SN7Ws: The two tall versions sound identical and are absolutely astounding in their musicality, sound stage and imaging. The shorter ones might singe your ear-hairs with their highs(unless your system is laid back in the upper registers). the TungSol 6SN7GT round plates(not with the mouse ears though)have very much the same attributes as the tall Sylvanias and work excellently together. I'm using one each in my Cary SLM-100's. If you switch out your Sylvania(bottom getter from the 40's) VT-231s for either of these: Your biggest improvement will be in depth of sound stage. I suppose you already know to shop for the lowest noise tubes possible, though finding either of these at all is getting harder by the minute. I've tried the Ken-Rad bottom getters and the VT-231s were a bit more natural, though not by much. I've not tried the CBS 5692 Red Base as it's scored consistantly low on every 6SN7 family tube shootout that I've read.