Yeah, I have very little faith is current production rectifiers. FWIW below is a post from Steve a couple years ago regarding current production vs NOS (emphasis added by me).
Quote:...New Old Stock is the real deal. Those who like to push the envelope of what is possible with their amplifier will often go down this path with no regrets. For one thing, the tubes not only sound better, but often last longer, in some cases like with rectifier tubes up to 10 times longer.
Rectifiers are a subject all in their own. Russian rectifiers are acceptable, everything else is a no-go from a reliability standpoint with some rare exceptions that are very pricey. My advise to all Decware amplifier owners is to find yourself a New Old Stock 5U4 or a 5R4 that has never been used and comes in it's original un-molested box. Consider the current production rectifier tube we ship with the amp the best sounding and most attractive option that will last long enough for you to find a real N.O.S. replacement.
Finding N.O.S. tubes is easy, even on eBay there are millions. Since you only need one or two you will have more to choose from than you know what to do with. Finding quantity of these tubes is another story. If Decware could secure reliable inventory of 1000's of N.O.S. rectifiers, it is an investment we would gladly make but in 25 years is has yet to happen. Because we can't find N.O.S. tubes in large quantities, even batches of 100 would be gone in less than 30 days, we feel there is no point in even trying.
For the customer it is easy, just find a N.O.S. 5U4 tube on eBay that is unused, and in it's original box for $40 and it could easily last for 10 years or more and sound better the entire time.
As an amplifier designer, it is possible to create circuits that baby the rectifier tube by limiting inrush current, using smaller capacitors, running higher voltages with a choke and so on. Correctly done, this can make a Chinese rectifier tube last the full rated 500 hours or more. The problem with this is that it changes the sound quality of the amplifier well outside what we find acceptable. So, we have to make a choice, do we design tube amplifiers to baby the crappie rectifier tubes being made today, or do we design amplifiers to use REAL tubes. Of course the answer has to be REAL tubes, because we make real amps.
FWIW I would not leave the amp on 24/7. I would at least turn it off over night. I usually turn mine off if I'm not going to listen for an hour or so.