Tube Preamps Should Have This Feature

Hmm I might strongly consider another tube preamp that allows me to bypass those sometimes PITA tubes. Good to know. 

mulveling, I thought tubes didn't like on/off cycles. 

I wait for 30-45 minutes after turn on. Do I hear a difference ? YES !  First ten minutes is no go, after that you can go but better wait a little longer. Tubes or capacitors or both, it's exactly as VAC recommends.

Yeah, reissue tubes if you must save.

mulveling, I thought tubes didn’t like on/off cycles.

@inna Maybe, if you turn gear on/off a dozen times every day. Who does that? Or if your component slams full voltage on plates immediately, before heaters have a chance to bring cathodes to temp - but again, who does that? Most hifi gear has some kind of soft-start consideration.

Most small tubes are pretty robust and will outlive our interest in them :) A few duds will emerge, that’s just the way of these things. We audiophiles generally over-worry about tube life & care, IMO. I’ve stopped worrying about it so much, and just turn a tube component on when I want to use it. I have not noticed significant changes in warmup with tube gear (unless it’s a hybrid with transistors in there), but don’t discount maybe some cap or resistor might prefer to be toasty. But I think generally you want to minimize heat on those components - especially electrolytic caps (like 10-years OOP BlackGates)!

For all the concern over tube life, the great thing is you can always replace them! A high end amp using OOP transistors might be SOL unless your manufacturer stocked up well (and is still around to service). Transistors are far from immortal, and in fact they can be a LOT more sensitive than tubes to over voltage and overheating conditions. 

I have found the warm up time required to sound the very best is highly dependent on the make and model. For instance the Audio Research Reference 5 and SE had a very distinct ~ 10 - 12 minute warm up sound improvement… but a signal going through it was required! It was very distinctive… you could turn it on for an hour but the sound improvement happened ten minutes after a signal got sent through it. I thought I was nuts, so I got on a forum… and I was surprised to find detailed discussions about this exact behavior.

Now with the ARC Ref6se… no notable change from the moment the one and a half minute internal warm up and the auto mute comes off.

Other equipment has been different. But an individual piece tends to be completely repeatable.

To my needs experience,  solid state stuff needs much more warm up time than tubes stuff which sound already fine after a few minutes of warm up.