That's true, but the distortion characteristic of tube amps is usually more or less "monotonic".
That means that the distortion increases gradually as the level increases (while sold state amps play very cleanly, then distort once they reach a certain point).
Since our ears perceive small amounts of distortion as "loudness", this means that, as the tube amp gets louder (really),
we hear both the real increase in loudness AND the increase in distortion BOTH as increases in loudness.
So, we hear the increase in loudness when that tube amp goes from one watt to four watts (with increasing distortion) as being larger
than the increase between one watt and four watts with a solid state amp (with no increasing distortion).
The result is that the tube amp may seem both "more powerful" and "more dynamic"
(if you think about it, that gradually increasing distortion acts like a sort of virtual dynamic range expander).
Of course, the price factor comes into play; since you can often get a much more powerful solid state amp for the same price as a less powerful tube amp.
Originally Posted by whoaru99
Just to clarify, you mean may sound as loud without an unpleasant a type of distortion, rather than "without" distortion because the distortion is
there, in spades, even if it's not like driving an ice pick into your ear.
I have a ~30W tube amp and I think it sounds pretty good, but by the same token I don't proclaim it as equivalent to 60W of ss power because the distortion at that output might be somewhat more tolerable.