The cj uses only one tube PC7388 a tougher version of 6922. My volume at lower end around 20. CJ owners will know this. I have Pass xa25, Prima Luna evo 200 (ge 12au7 & orion) power tubes stock el34 for now.
Ok.
Pass Labs XA25 aka 20db gain transistor amp.
I can see why you would need a high gain pre for that.
Better sound meaning better tubes for the Etc3...
There are threads on this forum debating that already.
But I've seen it written that Philips SQ88CC Holland Herleen ca 1960'sh tubes are suppose
To be one of the clearest neutral and punchiest tubes still with that inner glow intact, in a CJ Etc3.
So.. another tube pre then. 25 ish gain with low enough noise floor...That usually costs money.
I think the above mentioned tube might get you a lot of those CJ Et7 S2's qualities, not needing an actual pre upgrade.
That is ... if this is what you actually are looking for as an improvement then.
You want better sound.
A very loosely defined goal.
Save money. Buy the Et7? Maybe the best bet!
CAT SL 1 pre optionally? But then only if it has the 46 stepped volume module...
Budget 5 large...
I'd try more tubes first, but that's me.
Best of luck!
Imperial