If NOS pre or power tubes became unavailable altogether, what new tubes would you buy?

@almarg , I remember your issue with the Sophia's and maybe they can't tolerate voltage levels in some amps. Tubegroover is having good results in a low current device; a CDP.
Which makes me wonder if the Sophia's would hold up in a single gain stage preamp. 
Al, although the high sensitivity of your speakers reveal the issue with hum, the specs of these tubes don't lie.

Hi Lowrider,

Heater-to-cathode leakage is not a specified parameter in the case of most tubes. For example, that parameter does not appear in the GE datasheet that is linked to in Sophia’s description of their 6SN7. Also, it’s not a voltage issue in this case, because even before they were placed in my amp all or nearly all of the eight tubes I received did not meet the 10 megohm criterion that Atmasphere cited as the minimum he would consider to be acceptable. And their measurements did not change much if at all during the time I was using the tubes in my amp.

What I and the other member reported in the thread I linked to is either a design issue or a quality control issue, albeit one that apparently would not manifest itself in many applications.

Best regards,
-- Al

Dear @jbhiller : You made an open question and I gave you an answer. This is what I posted in your thread :

""" If NOS pre or power tubes became unavailable altogether, what new tubes would you buy? """

my answer and firt post was: NONE, change to SS alternative.

NONE. What's wrong with?

Anyway and due that my target is not to change any one mind and that I like enjoy MUSIC, it's time to do it.

Btw, I left to all of you something to think about: if some one ask us why we own a home audio system, which could be our kind of answers?  maybe:

- I like to listen MUSIC at home.
- I'm an audiophile.
- I'm a Music's lover
-It's my hobby.

and maybe some other similar answers. Now, how is possible that all of us that likes MUSIC some of us just don't care  enjoy it listening the nearest way we can to reproduce the live MUSIC experience through our home system audio.

I care seriously about and that's why attend each week to listen live MUSIC. The other premise is that is me who decided each one single link/item in my system's chain, to be nearest to the real MUSIC,   NOT the corrupted AHEE.


Regards and enjoy the MUSIC not DISTORTIONS,
R.

Dear @tubegroover : """   your facts are not mine... """

my only fact/target is: reproduce the nearest live MUSIC experience trhough my home audio system. 

I can understand that your is different and I can't disagree with because is a self human been privilege.

R.

@almarg , thanks for the additional info. It’s good to know that heater-to-cathode leakage is not influenced by voltage, since I’m considering trying the Sophia’s in my preamp.

Al, although the high sensitivity of your speakers reveal the issue with hum, the specs of these tubes don’t lie.

Specs is the wrong term; I should have stated "measurements" since you knew about Ralph’s criteria in this area. I did look at the GE datasheet and saw that Sophia was comparing their tube to a well known NOS tube’s specs. To be honest, I never heard of heater-to-cathode leakage until your findings.