Replacing Sovtek 6922 for NOS

I have the Logos, the newest hybrid amplifier from Pathos Acoustics. The original tubes are Sovtek 6922. Any good? I suppose I could get a much better overall sound if I upgrade to NOS tubes within the ECC88/6DJ8 family. Amperex (BBoy) and Mullard seem to be very good. But I really would like to know which are your preferences. Thanks. tgm
A twist of fate meant that my plans to experiment with the JJ Tesla E88CC where put on hold and instead I procured a pair of Brimar CV2492 not CV2496 as I am wont of calling them. There are quite a few valves bearing this name, OEM issues withstanding their pedigree seems blurred with Mullards GECs and even Amperexes. They have a ring of studs on the shield that throw back a glow all around the inside of the tube and star like protrusions on the main body of metal work. Gold pins.
The result, an outstanding improvement over the Sovtek 6922 although subjectively you might prefer the Sovtek bass in your system. Smooth and atmospheric with attack and great mid layering, revealing every nuance, highs splashed and tingled with focus and natural decays. In the first 12 hours they lacked a little menace but once settled in they could strike with bags of intent when needed. Brings older recordings alive and can make some modern ambient stuff sound down right eirey. What now? JJ/ Tesla are 1/4 the price, Telefunken, Siemens, Amperex are 4 x the price. Time to settle down for a few months.
Siemens 6922 - yes ben, you could say thin in the midband, like swapping your speaker drivers from paper+silk to ceramic+titanium. However they sound clear and strident and their direct attribute draws you deep into the music, holding the tonal nuance ever so well. Their bass rocks when asked for, remaining polite and controlled otherwise. I like them for the Goldberg variations, however the Brimars win on all vintage sounds.
In my Blue Circle preamp, I tried a few different tubes.

The Sovteks seemed kind of rich, but lacked resolution and sounded a bit fuzzy.

The Philips JAN tubes had good clarity, but lacked warmth.

I wanted a bit more warmth and richness, so I was told to stay away from Siemens, as their forte is clarity as opposed to warmth.

I tried Valvo 7308, and they seem to offer the best of both worlds since I plugged them in. Great clarity, but more of the richness I was looking for.
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