Hello,
congratulations from me first and welcome to the Ultimate family.
Also very brave of you to go straight to C3G.
It's still something I'm holding back on my Junior.
Which capacitors did you have fitted?
Remember that they still need to be broken in and will actually open properly after 200 hours plus.
Until then, there may be small dips where it can get a bit strange.
The new tubes also need a certain amount of time to break in.
So the bottom line is that everything gets better with time.
Personally, I used the time until the capacitors broke in to let the tubes play in at the same time.
I only really got to know Ultimate after 5-6 months.
At the moment I'm still listening to EL32 Mullard with the 5751 Tungsol (NoS) from Ez81 Nec, but I've switched to 6bw4 Sylvania.
With the Atrium it got too warm for me over time, but with the Auteur just right.
I will try another rectifier with Atrium.
But first I have to check what I have in my aresenal.