Tube preamp reliability vs SS?

Conrad Johnson has three small tubes on the sockets.  Replacement is as simple as pulling one and, after replacing damping rings, pushing new one paying attention to orientation.  5 min job.  When I was young, we had TV full of small tubes.  First one was replaced at about 10 years.  I would base decision only on the sound in my system and the reputation of the company.  SS (even SMT) can be as unreliable - it depends on design and quality of the parts.

You can listen before 30 minutes, you don't have to wait that long. The warm up time, optimal performance, for tube gear varies depending on manufacturer. Changing out a tube will not void a warranty. It is pull out the old and plug in the new, simple as that. Now on a tube amplifier it may NOT be as simple as that as biasing is required and how biasing is performed varies among manufacturers'. It can be quite simple to a royal pain but this isn't about tube amplifiers.

Tube life? well that depends on the circuit. Conrad Johnson gear about every 2-3 years in my past experience with their older gear. Their newer preamps  running 4 hours a day I would venture about the same but it will vary on the quality of the tube used. Chinese tubes don't last in my experience, even some of the premium ones at those premium prices although some sound quite good. The better tubes are from the golden age of tube manufacturer from the 1930's through  the 1970's. These would be tubes made in Germany, UK, Holland, Canada and USA. Also some of the Russian tubes are also quite rugged and will last longer. The older the tubes, generally the more expensive they will be. There are many reputable tube vendors to purchase tubes from as well as the manufacturer. A further word about tube preamplifiers, don't worry, be happy. They are as reliable as SS. I have been using tube pre-amplifiers exclusively for the past 30 years and have NEVER had any problem other than replacing tubes and an occasional fuse and I must say they are fun to own. You can try different tubes to suit your tastes but you don't have to.

Good advice and comments  given above.  The tubes  use in preamplifier are typically  low signal and often run conservatively, they can last year's if of good quality.I have a Quicksilver preamp that I  use in a 2nd system, it's 's 23 years old and hasn't  missed a beat since the day  I bought it new. You can tailor the sound via  trying different  tubes. Simple  modification like capacitors or better fuses make a difference as well ďue to the simple  circuits of most tube preamps. My advice, get one that the  builder provides a high quality and  robust power supply. Power supplies  matter.
Good luck,
Charles,