amplifier longevity

The only piece of electronics I ever had fail was a HK receiver. No other amp, SS or tube,

I built my Hafler 500 at my desk in my shop in 1974.  Recent trip to my engineer showed it slightly out of bias.  Other than that, measured as if brand new and still sounds great on my Maggies (bottom end).

Cheers!

The one longevity issue that is universal is that you need to keep the heat as low as you can with plenty of circulation and a fan. Heat is the destroyer of electronics.

Half of this makes no sense.
I scratched out the part that does make sense.

I traded them in for a set of Class D monoblocks 3 years later because I couldn't stand the heat and the tube maintenance. 

At 10 years old they ran like champions and had not one issue.  

But here we agree and have experienced the same.

Not counting my first tube amp, a VTL..... …

My mid 1980's Acoustat TNT200's worked when I purchased them last year. I just had them rebuilt and modified by Roy Esposito, a former Acoustat Engineer. They worked 35+ years before I had them rebuilt.  I suspect they will outlast me...