Can you do anything to make power tubes last longer ?

Your bias current is usually measured across a 1 ohm resistor so that mV=mA.  The meter measures volts but because the resistance is 1, then the number is the same.  So a custom meter will measure volts, but it will say amps.

if your maker didn't order a special meter dial, it may say mV, but is actually reading mA.

There is a post above that contradicts this and I'm not sure what the poster meant.

Jerry

The 60’s Mac amps also very famous for long tube life… I have some 1965 tubes … Tele that still test well.. 

@whart I need to copy your dusting rigor…. wow…. i would never get away with photo like that…..

So you choose particular amps for longest tube life. That's interesting approach, not always works, though.

No… luck as I inherited the MAC which i abused as a young punk… The Music Reference connection born of my experience selling gear Roger designed and built w Harold Beveridge… also imo a genius… RIP….

mulveling,

Could you suggest particular Amperex EL34 that I might want to try later ?

Perhaps, I should also try Sylvania 12AU7 black plates from 50s as well. What difference would they make compared to RCA black plates from 50s, I wonder ?