Can you do anything to make power tubes last longer ?

@inna congrats on finding the Mullards at hopefully not too an outrageous price. I’m sure you’ll be very happy you did. I had similar experiences, though different amps but the same tubes, and found that the SED never gave me as good an experience as true Mullards. Ralph brings up a very good point of warming up the tubes slowly at the outset. It’s probably (at least one of) the reason he builds his amps the way he does.

marco1, thank you.

Yes, so now I have 12AX7 Mullard long plates in the preamp, 12AU7 RCA black plates in the driver and Mullard EL34 XF2 power tubes. This is done. Now I will have to think/experiment what to put in the phono stage, since I don't care much for the Brimars that are currently there.

The price was reasonable. A little more than new SED tubes cost.

I’ve always liked the RCA 12au7 black plates. I remember discussing them on another thread with you and Mulveling. I’m currently using RCA 5816A black plates as a driver in one of my amps. They’re a little more refined and warmer than the 12au7 and although I’ve never used them in combination with Mullards EL34 I think they would compliment the Mullards nicely.  Something else to spend your money on if/when you get the itch 🤑

Next year maybe, I spent enough already. I would be cautious to take the sound in  warmer direction compared to how it is now, that would also probably be the case if I replaced the RCA black plates with Mullards for the driver.

Yes, we discussed it before. You and mulveling helped me  choose 12AU7 tubes.

"Next year maybe, I spent enough already. I would be cautious to take the sound in  warmer direction compared to how it is now” yeah, next year you will be one year older, and hopefully everything around you will be “warmer” LOL