Tube Amplifier Sound Characteristics

Everyone focuses on the tubes, because they are so obvious and easy to change- and there are indeed differences between tubes. But tube amps really are no different than anything else in that everything matters. Equally important as tubes are transformers. Equally important as transformers are diodes, caps, circuit design, etc.  

If tube amps were made with diodes that plugged into receptacles on the top that could be changed by hand as easily as tubes then mark my words everyone would be talking about diode rolling and the virtues of amps build around their favorite diodes. Because I have swapped and upgraded diodes and believe me the difference is huge and obvious and can take a flat grainy edgy amp and make it liquid warm and deep. 

In other words it really is just like ghdprentice says above, a system is the sum of all components. Only thing to add, this carries straight on through to the components used within the components.

On the left is warm romantic, on the right cool neutral?

Okay having studied your requirements the solution is obvious. Take a clean piece of paper. Draw a rectangle about 5" wide by 2" high. Label the left, "warm romantic". Label the right, "cool neutral". Take a crayon, color this blob yellow. This is your tube amp diagram.  

Now we do the same for solid state amps. Let's use blue for solid state. 

Now if you followed the instructions well you should be looking at a green rectangle. Smack in the middle draw a great big letter "S". Now divide the "S" by drawing a big ol' vertical line right through the middle.  

This is where you will find your amp. The more of these $ you make the better the amp you will find. 

Surely you mean multi-dimensional Venn diagram?