Tube preamplifier lifespan

the owner of psaudio told me that they do, lifespan of only 20 years"

With the exception of the amplifying and rectifier section(if fully tube) components -tubes vs discrete transistors/OP amps, they essentially have the same caps &resistors etc.

Perhaps the SS devices(transistors/OPamps  and diodes) are what will qualify lasting longer comparing the 2?

dunno, but it makes me worry since i have the matching BHK 300 monoblocks each with 2 input tubes

Rectifier tubes get very hot and don't last as long. One reason I purchased the BAT VK-80. The downside is some tubes are very expensive and some tubes just don't last as long as they should. If you have more of a minimalist type tube preamp that uses just a couple of tubes it may be more reliable especially if it uses cheaper and more common preamp tubes.  

it's not the tube life that i'm worried about, the 12au7 tubes are relatively cheap , and there are only 2 of them. it's the comment that the design of a tube preamp won't last nearly as long as a solid state preamp

Onehoursepony,

Utter nonsense.  The only thing that does not last as long is the tubes.   There are Mcintosh, ARC etc... tube preamps still in the field.