Can you do anything to make power tubes last longer ?

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.

@inna 

That was one of the reasons I went with Hybrid stuff. I currently have PS Audio.  The BHK preamp that uses two 12AU7’s and the mono blocks are currently using 6922’s.  All of which can be affordable and last a fairly long time.
My downstairs mono blocks use 4, 6HB5’s in each and they starting to get expensive to replace. I’m still using an ARC SP9 MKll Hybrid preamp with them and it uses 6922’s also.

Yes, not inexpensive. I made approximate calculations. Unless prices for NOS or near NOS tubes go much higher I will need about $40/$50 per month on tubes. This is no problem. But I need only four power tubes. Excellent NOS 12au7 tubes from a reputable source or ebay can be had for about $50 each. 12 AX7 are often two/three times more expensive. Well, the NOS 12AX7 long plate Mullards that I have in preamp were $450 for a matched pair. But they should last for a very long time, so no worries.