Reminder - It might be time to replace the rectifier tube if you have one.

Having owned tube components for many years, I’m used to replacing tired valves. Usually, weakening dynamics are the first indication. Three years ago, I purchased a DAC that has tube output stages and a tube rectifier. The dealer didn’t how long the rectifier life was. He just said ’a long time’. Last week, I replaced it with the same NOS brand/model - different year of manufacture.

The old one was quiet, nice tone, excellent dynamics - along with a fairly forward & lush presentation. The fresh replacement was very similar but with a much deeper/wider sound-stage. Instead of forward & lush, the image was cleaner with more instrument separation. The dynamics were pretty much the same. I’m pleased that the rectifier had a 3 year life-span.
It could be a simple case that the new rectifier tube is just a better fit with your dac and has nothing to do with the previous tube being worn down.  
Those rectifier tubes are more often than not just forgot about, usually because of their long expected life span, but as the OP points out it sure pays not to ignore them and they are usually a great place to start your tube rolling for the greatest results. Enjoy the music
Instead of "3 year life-span", I prefer to measure in hours. I've had my new tube preamp for 1.5 years but only listen about six-hours a week.
Should I still expect 3 year life-span?
@dweller , I believe your breakdown into hours used rather than years of life is the right way to go when evaluating your tubes life. Enjoy the music
By my careful calculations, Dweller's rectifiers will last 37 years. I'd replace 'em at 36 to be safe.
My calculations were extremely careful although very likely utterly inaccurate.
In my amp the rectifier, it can take either a 5AR4 or 5U4G, makes a huge difference in sound quality. I rotate different ones in from time to time they seem to last pretty long at least 2 years for me and I listen constantly. I will also say a 5U4G sounds much better than a 5AR4 to me.
Rectifier tubes I have seen old 50s Mullard 5ar4 rectifier still operating well
after 10 + years. The Type  and quality of the rectifier has a lot to do with it ,as well as how hard they are run.if  it a well thought out design it is around 35% of its potential . That is what my Lampizator dac
runs the rectifier at, which I had changed from a 6x5 to a 5u4Gwith a new 5 volt transformer. This  5v rectifier puts out 3 Amps vs 1.2, which gives a ton of control , and  operates  at under 40% potential .This 5u4G 1950coke bottle type which is excellent and much less $$ then the most popular 5ar4 rectifier tube.
I had mine replaced when I turned 50. I heartily recommend the procedure, but get an experienced surgeon. Good luck

Yeah, my 'rectification tube' isn't as 'responsive' as it used to be...*sigh*

Not replaceable, sadly...but fortunately there's *ah* certain 'work-arounds' that seem to induce agreeable response...

@jpwarren58....I  hear you...the main valve in my on-board amp turned out to be a mutant from delivery.  The new one was slipped in without major disassembly (fortunately).  They later updated me with a new time/correction circuit with a reboot app....

It's even Bluetoothed!  *L*

I be Borg now. ;)  We will All be assimilated..

No AI for this rig, though..... 
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