Part of the rational is ease of implementation. A tube pre-amp does not need to be biased (there probably is an exception somewhere), the tubes usually last a lot longer and are less expensive (for current production), esp on a cost/hr basis. Tube power amps may require biasing (unless auto-bias), power tubes typically more frequent changing and generate more heat. There are exceptions to pretty much all of this, but in general a tube pre-amp is pretty much plug and play, as is a ss power amp.
Tube sound Comes, mainly, from? Pre or Power?
I quite like the tube sound and I have become accustomed to it since I was a little kid. So in my own pursuit of the tube sound I have come up with a hypothesis, and I am not sure if it is in fact correct. The way I see it, the phono section and the preamp section pull about a 50-100 multiple the of the amplification done by the power section. Would it be reasonable to assume that the majority of the tube sound would come from the pieces of equipment that do the most amplification (phono and line pre), in terms of multiples? If so this would explain a popular tube pre, solid power combinations that many people utilize. Let me know what you think. I am very curious. Thanks, and please keep in mind that despite the fact that I have been listening to tubed equipment since I was born, I know very little about it and I am in the process of building up my first system.