I have not heard either of your choices, a few thoughts:
12ax, 12au
I truly like the sound and full features of my Vintage McIntosh mx110z Tube Tuner/Preamp with many 12ax and 12au (I use a Chase RLC-1 Remote Line Controller with it).
6sn7s
My friend heard my Cayin Integrated's 6sn7 and 6sl7’s here, found deHaviland and had Kara make him a new Preamp with 6sn7’s, AND tube rectification. She ordered the specific transformers she needed, so it’s not quick ship.
http://www.dehavillandhifi.com/UltraVerve-Preamplifier.htm
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REMOTE BALANCE
McIntosh has remote balance
which I love and use frequently, especially compilations that include tracks from different recording sessions, personell, I just listened to this, and made small but beneficial tweaks to many individual tracks
https://vinyl.sonymusic.com/products/sade-the-best-of-sade
And, a CD yesterday, I only tweaked a few of these tracks
https://www.amazon.com/Friend-Mine-Bill-Morrissey-Brown/dp/B0000003U6
Does Prima Luna have remote balance?
Either have a dedicated balance button on the remote?, or do you need to get in Menu’s?
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I might prefer the McIntosh, however
PrimaLuna talks about tube rectification
Tube rectified
"In the world of preamps, experts agree that tube rectification is the gold standard. It’s quieter than solid state rectification, dropping the noise floor. And it offers the most natural, textured, and vibrant presentation because the circuit is now pure tube. But because it is expensive to implement, you’ll only find it in the top of the line models typically costing $10,000 or more. Finding a preamp using one rectifier tube is sweet. PrimaLuna goes even further using two 5AR4 rectifier tubes in a dual-mono design to present your music with a three-dimensionality that will give you goosebumps."
The deHaviland has tube rectification, and they sent my friend alternate tubes, we were surprised how much the sound changes

