is getting a tube pre a valid option with ss amp?

Adding a good, basic tube preamp will increase the presence and sound stage of your system. At one time I didn't believe that it would make any difference, but now that I have tried it, the difference is huge! I say basic because preamps with allot of bells & whistles have too much going on under the hood and they can dampen the sound. Look for a preamp that has as few tubes installed in it as possible- say 1 to 3 tubes, not including a tube rectifier if it's there.

More tubes are required if it's a line stage + phono preamp combo. That is the only exception. I have seen basic preamps with a single tube that work exceptionally well. A single tube, set up correctly has considerable gain. Most amplifiers have extremely sensitive, high impedance inputs. You may not know this, but preamps (line stage) attenuate the signal more often than amplify anything! An incoming signal of 0db to most amps would cause considerable damage to your amp, speakers AND possibly you in most cases. This is why passive preamps (with zero active components) work so well. So- if zero tubes/transistors works so well in the line stage, why should a preamp have multiple tubes? If there are tone circuits, etc.. extra gain stages are necessary. A basic preamp does NOT require a half dozen tubes give or take a couple.

To answer your question directly- If a design can work excetionally well with, lets say 5 components, why use 10? The individual who chooses to make a 10 component design isn't as good a designer. Complexity does not in any way prove an engineer is good. Designs that are complex when they don't have to be shows very poor judgement. If there are two machines and one has more parts in it than the other, yet they both work exactly the same, wouldn't you choose the machine with fewer parts? It's likely more thought went in behind the model with fewer components and it will work better anyway. As a last comment, devices with fewer compoents statistically break down less often.

OK- Component limitations are getting confused with engineering concepts. Ganged tubes can produce lower impedance outputs and high power levels. Same with transistors. We all know that. It has nothing to do with what I said. The condensed version of my last statement is, "If something can be made with fewer components yet remain as effective or better than a design with more components, then the conservative design approach should be taken." There are no negatives or limitations to that design philosophy economically, statistically or performance-wise.