Primaluna?

I don’t see many experts here on the topic, and the worst offender is this fellow named Millercarbon who declared:

I think some are starting to finally figure it out.

@brylandgoodman Wondering if people generally replace a single bad tube or if people are replacing all tubes of that type when there’s a failure.

Not sure if anyone addressed this question in your post as the thread kind of got into a debate. It seems that PL and Tekton are brands where this happens. You can learn more from threads where people stick to answering questions with detailed personal experience.  

I owned a PL Prologue Premium preamp that I traded in for a PL Dialogue Premium preamp. Never had a bad tube problem. I did experiment with different tubes to change the sound and always used matched pairs of tubes (the inner two tubes were the ones I changed on the PL preamps - this is where you can hear a difference. The outer two on each side, not so much).

I own a CJ 17LS2 preamp and change out the tubes with matched pairs to change the sound as well.

I recently purchased a Don Sachs DS2 preamp and will probably eventually try a different set of tubes there. Again, it will be a matched pair.

Note that the three brands of preamps I have experience with all use different tubes and they do sound different. That was my intent. 

The interesting undercurrent to your question is, in addition to the technical one of whether it would be safe to change out just one tube or would it hurt the equipment, is whether you would be able to hear a difference. This depends on your ears, your source, and your speakers. Your results can easily be different from what others experience with even a slightly different combination of gear.

I also own a CJ 66LPS tube amp. It has manual biasing, which is not a big deal to do as the adjustment screws are set on the top of the deck next to the tubes. But hey, not having to worry about it could be fun too!

My opinion is circuit protection is important. If you read enough posts, you can form a learned perspective about this. The most unfun thing about audio is not being able to listen to a piece of gear because it is not working properly. I am not technically proficient and people like myself need that protection (I have learned the hard way to turn off all power whenever I change out anything!) 

I am off on a tangent here but want to share that you never can tell what equipment will really gell with the rest of your gear until you try it. Put another way, you might like the sound of preamp A compared to Preamp B. Then you switch out another piece of gear, for example the DAC. How do you know whether the new DAC would sound better with Preamp B unless you try it in your setup? Does that mean Prreamp A is not as good as initially thought? (No...). There is a reason why people have multiple pieces of gear!

Whoops, one more thing! My Don Sachs preamp was better at 50 hours than brand new and better again at 100 hours than at 50. First time I have had a liquid sound to my system.

Thanks for listening!

Dsper

@jerryg123 

But I own an Aprilia so therefore it's the best!

I agree with you. There are fantastic bikes available from many manufacturers. Just like there are fantastic audio components available from many manufacturers. There's no universal "best."