Power output of tube amps compared to solid states


I'm having a hard time trying to figure out how tube amp power output relates to solid state power output. I've been looking at the classifieds for tube amps and I see lots of tube amps with 50w or 60w output, but nothing close to the 250w output typical of solid state amps.

So I have no idea what type of tube amp is required for my set up, right now I'm using totem forests with a required power rating of 150w-200w at 8ohms. The bass is so powerful on these that I have the sub crossover set to 40hz.

My question is, are tube amps so efficient that 50w from a tube sounds like 150w from a solid state? Or will 50w output from a tube severely limit how loud I can play my speakers? If so, are tubes usually meant to be driving super-high efficiency speakers?

I had previously tried a tube pre-amp with a solid state power amp (both musical fidelity) and didn't like the results because the imaging suffered greatly, even though the music sounded nicer from a distance. Now I want to try a solid state pre-amp (bryston) with a tube power amp (no idea which brand to look at), but I don't know how much power output I need or if it will even be possible with my speakers. Does anyone know what I would require?
acrossley
Orpheus10 and Mapman, the reason tubes seem more powerful has to do with the way we perceive sound and the different ways that tubes and transistors make distortion. I would look at some of Arthur's comments above- they are right on the money.

I think I also had some of this explained above too- if I need to clarify it just let me know.
Atmasphere.

No further clarification needed on my behalf. Transients are key. Its pretty clear to me that its mostly about details relating to distortion and how different factors contribute to that, as you say.
I am going to jump into this "tower of babel" with all four feet and state my qualifications for doing so.
Before I became an Audiophile, I was an electronics technician who knew all the electronics formulas. "If you can not measure it, you can not hear it" was my slogan.
After I became an Audiophile, I laid my meters to rest. I can hear things that no meter can measure.
"Is this dog better than that dog"? Unfortunately, no one can answer this question but you. This is not a scientific arena, this is a very subjective audio arena.
I have to believe science plays a role here, there is still good design and bad design and I believe is governed by understanding electrical principles. If that is not sound, no pun intended, you are not going to get good equipment. Now as to the seasoning that a knowing chef wishes to use, that is more subjective, and the art in audio engineering IMHO.
I think it is useful to differentiate between matters of opinion and matters that do involve empirical differences but differences that we may not currently be able to accurately measure.

We do not currently measure amplifiers playing actual music and so do not really look at harmonic, IM, and other types of distortion products amplifiers actually produce making *music*. Furthermore, and much more importantly, we know only a very little bit of how to "weight" the results because we know rather little about how the ear/brain system actually works - what sorts of distortions make music unpleasant or unrealistic and what sorts really just don't matter all that much. (Of course we do know some of that, as Atmasphere & others have mentioned.)

Why some audio amplifier designs tend to sound better or more realistic may not be easy to describe empirically but it is at least not entirely a matter of opinion. Preference for dogs is. :)

(Ok, if you establish certain criteria, such a strength or cuteness, one could of course rate dogs quantitatively as well...)