while waiting on a preamp for my DEFY 7/6550's

Interesting comments. Seems I've read similiar comments on differences in Jadis' models....anyway I could also make comments on at least one other famous tube amp manufacturer, american. That I have issues with the sound. So I'm not going to knock Jadis, based on experience of other tube amps.
The KT90 can be a tad 'steely' as i mentioned. But it does have nice separation of bass, mids, highs. Highs roll a tad, but hey its a small trade off for its other qualities. So seems my first Jadis purchase was a good one, JOR/KT90's. Now the JOR with other tubes might be exactly what others need for their style of music. I'm just saying what works for me. Though i am willing to give the stock 6550's in the Defy a chance. btw the 6550's are what Jadis stocks, the Svetlana/russian /SV6550C tube. The tubes look awesome. Obviously I was wrong in "testing out" the 6550's in the JOR w/o proper biasing. Jadis biased the Defy 7 for the 6550's at their lab. So I'm in for game. btw the pre is the Ming da 2A3 which I will let Ken here in BR set up on his system first as he has multiple pres to compare with. This way when we hook up the pre he can tell me whats going on with what. If there is an issue he'll know how to track down some adjustments/roll tubes. Like Joe just mentioned, how much is it really worth to us. I'm trying to make this my "last amp". Also note: IF the JOR came with the 6550's and the amp sounded like this on orch, I'd sell it immediately. I mean its bad, as in poor, not "bad" as in street lingo.

Great thread, even though I have never owned a Jadis component, I recognize a few of the posters here and thought I would second Mechans and Newbees posts. There is a tremendous range of tuning to taste that can be done with signal tube rolling. I have an old Manley 350 monos
in the closet (currently run a CAT JL2) that use the first generation EI KT 90. A great output tube! The Manley's sounded better than the JL2 (both with stock signal tubes)
when I initially installed the JL2. I have done a massive amount of signal tube rolling in the last year. The CAT is now at a level the Manley could never reach. I have to mention Trelja's post here for a moment. He refers to the 12AX7 position having a bigger impact on the sound than the 12AU7 slot. When I began rolling the signal tubes in the JL2 (12AX7, 12AU7 and 6922's), I had the same impression about the 12AU7 slot. The differences heard in the other two positions were much more pronounced. It took a lot of perseverance to get the dramatic improvement from the 12AU7 slot that I had achieved from the others.
A quick side point to Bartokfan. If you are using the Sovtek 6922 in front of the KT90, that steely sound you hear (and attribute to the KT90) is coming from the Sovtek (the worst 6922 I have ever heard). The best of the signal tube families IMO is the 12AU7 family. There are an almost limitless amount of tuning options in this family. I will never finish this post if I try to describe all the signal tube options here. I posted a lot of my thoughts on them on AA under the moniker posbwp55@msn.com. What really drew me to this thread was a google search for Ming Da 2A3 preamp. I have heard it is a giant killer. I am currently using the CAT Ult MK2. I will probably try to get a 30 day audition soon. Bartokfan, when you here more about this pre please post it here. I am unfamiliar with
the 2A3 and 6SN7 tubes used in it but it does use the 6922.
If it is close to my CAT with the stock tubes I guess I'll have to figure out two more tube families (oh no $$$). One quick comment on the 12AU7 of choice, all you guys that haven't heard the E80CC in this position are in for a treat (Tungsram). It is not a direct replacement, but I have not heard of a circuit it failed in yet.

Bart