Do tube amplifiers improve with age?

@larryi Tubes and caps typically aren't perfect one day and bad the next. Sudden failures can happen but its not the more common way that they need replacement. So they do fade away over time. A power tube with 1,500 hours on it isn't as good as a new one. I spent years building and rebuilding tube amps and kept a tube tester around to keep an eye on things. You could watch them age.

Most tubes spend the vast majority of their life changing very little, and at the end, they decline quite rapidly.  But even then, when they begin to test weak, depending on the amp design, they can still sound fine.  I had a set of 6sn7s that began their end of life plunge, as measured by my Amplitrex tester, so I contacted the manufacturer to see if I could safely run them.  I was told that the amp should sound fine until the tube is very close to death so I should run them until they quit.  In my current setup, i run tubes of unknown usage prior to being used in my amp and linestage and so far, they are still going strong for the past 15 years (348’s, 349’s, 310’s).

Caps, particularly electrolytics, do age; my only point is that they typically don’t do so as quickly as some think.  Some resistors, particularly carbon composition types, will in time drift in value.  But, to me they sound better than other types in certain applications so one lives with that.  I know a builder who uses some extremely old resistors in his best builds and his stuff is crazy good.  There is nothing as pretty as seeing sixty-year old IRC resistors used in a new amp or restoration.

That GAT2 is the best piece you own, but you have a very nice system.  No it will not improve with age, but your ears are breaking in nicely.  And, stick with the OEM tubes, they will last for a good long while.  When they need to be replaced they will talk to you.  Please don’t discount what I am saying about your ears, you really are adjusting to your system, it takes time.  The more you listen the better a good system like yours will sound to you.  There is nothing you are describing except a very good story.

  After break in , no. Maybe your musical experience has improved over time hence your increased enjoyment. And isn’t that what we truly search for ? So it looks like a big win from my viewpoint. Best of enjoyment to you , Mike B. 

A SE 300B purchased not too long ago is now in use as a permanent amp and not just a casual encounter.

To first experience the 300B, Input Valves were used of a very high quality and also receive wide appraisal. Power Valves selected to be used were classed as temporary or interim while options were considered.

An individual who was not communicated with across a few years came forward with a recommendation. The appraisal given for the recommended 300B was enough for me, as they had been compared to other 300Bs in other Amp's and held up very well. The individual recommending the Valves is a long-term 300B Power Amp user and has owned a selection of designs.

The Brand of 300B was selected, and the introduction of it to the Power Amp was just spectacular. The interim Valves, even though a move away from being Spec' had moments where there was really good impression made. The New Selected Valves, as a comparison, were an unfair match. The interim Valves were destroyed in an instant.

Have the Valves, or Amp improved over time? No. 

Has the appreciation of the Valves and Amp increased over time? You Bet.