I have an audio file that I sent by email to @jamesh because I’m not able to upload audio files here, it would help to better understand which kind of noise I’m hearing, from tweeter to woofer, close to speaker and far 1 meter from them.
As for db you are asking for, how can I measure it? Is there an iPhone app or something similar to suggest me? Thank you.
Prefer ketchup… 
Luca–This app is pretty good and not expensive.
Thank you so much @RonP, installed!
Well if all settings are correct, here the measures:
Close to speakers white noise from tweeter to woofer = 22/26 dB
At the distance of 1 meter = 20/24 dB
Playing music (Alison Krauss CD at volume level 38) measures:
At the distance of 1 meter from loudspeaker 56/78 dB
Thank you @Gary_M
Read all posts you linked me to… accurately…
Just asked to @jamesh by email if Psvane new S art series are recommended or not by PS Audio, what’s @Paul official opinion about? And maybe another question (I do not want to reopen my BHK Preamp and my Stellar M1200s once again to check): I received gears brand new a week ago… so what tubes are in from factory? The old ones 12AU7 or the new S art series? If a different model can be quiter and less noisy, which PS Audio can suggest to me?
What’s the dB level when the system is off?
With all the gears On and the BHK Preamp volume level at 0 mute measure is 17 dB, what I can define a totally silent moment in my listening room (wow quiet surprised about these dBs when my ears were hearing only “silence” and my expectation was a less less value - am I missing something in my acting?).
It means, as a difference between measures (gear On and volume on BHK Preamp at 0 mute = silence vs gear On and volume at level more than 1) that white noise I’m hearing from my loudspeaker is approximately 03/09 dB
For me, un-muted puts out 4dB of noise at the tweeter. I sit about six feet away and can’t hear it. You must be sitting closer, or your hearing is exceptional.
It depends… from how many glasses of wine I had for dinner 
As above mentioned I have at the tweeter almost the double of dB compared to you. My sweet spot is 2,4 meters (7 ft) far from speakers. Between tracks and during silent passages I have black deadly silence compromised by this “shhhhh’ just audible.
I repeat, I can live with it (one more glass of wine can fix a lot of problem - with moderation of course).
Anyhow if possible to reduce it, I’m happier. For instance with a PS Audio suggested alternative tubes I may buy on European market (online). Or some other trick…
@jamesh
Can P12 settings affect the noise I hear? Because sometimes it seems I can hear current fluctuation/modulation not a stable “shhhh” but something variable. Sometimes not.
P12 powerplants are regulated both with MW strenght +6, phase tune auto (-7 one and -4 the other) high regulation mode. THD from 2 to 3% as result.
Meanwhile, cheers! That’s all folks!
Good feedback so far; personally, I do notice a difference in noise depending on how well a specific pair of tubes are matched.
One other item worth checking is I prefer the 4ma bias setting vs the 5ma and it slightly less noise from my experience. It should come default as 4ma with the 12V tubes, but you may want to double check just to ensure it is set appropriately.
It’s possible that setting the P12 to low distortion mode will help a little, but I don’t want to promise you’d be able to hear or perceive this difference.
Thank you senna1a I can confirm JP7 and JP8 without connector jumper, so 4ma both of them.
Yes I changed P12 setting to Low Distortion mode but no difference is audible.
Brand new BHK Preamp… Brand new… problem solved guys! Hoping to help other in future I actually can consider closed this thread. Swapping the little boards behind the tubes I discovered the noise went from right to left speaker, following the TP25 board. Then PS Audio helped me, thank you so much, replacing it. Just fixed! New board installed the noise has disappeared. Great people and great brand PS Audio. Thank you very much.