Bob, it's great hearing from you! I'd really love to hear your CAT once it returns home. Knowing you, I'm sure it sounds lovely in your system.
I spent a good amount of time listening last night, and interestingly enough, the faults Albert attributed to this tube are EXACTLY what I heard. The dynamics are weak, and the sound just seems to lack the get up and go I demand. The high frequency distortion was also there in spades. Most curious was that female vocals took on a peculiar "lip smacking" effect where there should have been breathiness. Imaging was not terrible, but not up to the standard set by the JOR.
I did try the quad of JJ KT88 in one channel, and that seemed to help out a fair amount, but I was still getting the Sovtek 6550 effect masking the overall sound, so I am not 100% certain if a retube will cure things.
I went back and forth with the DA30 a couple of times, and it had a snappier, more lively, and easier to listen presentation. It's really a superlative amplifier, apart from ultimate power and not being the last word in imaging. My DA30 is one of the first integrateds Jadis ever built. I have been told by two people that later iterations modified the circuitry to enhance thermal stability of the amps, which has NEVER been in an issue with mine, at the expense of sonics. May very well be true in my experience. What it lacks in cosmetics, it sure makes up in sound.
The one combination I should have tried in retrospect was the Sovtek 6550 in the DA30. That would perhaps answer a lot of questions.
Still, this is the amp for the second system, and I'm probably putting way too much effort into the whole thing...
